Raise caving method for mining an ore from an ore body, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor

ABSTRACT

The present invention relates to a Raise Caving mining method for mining ore from an ore body comprising developing at least two slots ( 3   a,    3   b ) in a rock mass and leaving a pillar ( 9   a ) of rock mass to separate adjacent slots ( 3   a,    3   b ) in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise ( 6   a ) within the rock mass providing the favourable stress environment, mining by progressing upwards at least one production stope ( 13   a ) from the at least one production raise ( 6   a ), and drawing ore from the production stope ( 13   a ). The present invention also relates to a Raise Caving mining infrastructure, a machinery, a monitoring system, an automatic or semi-automatic control system of a Raise Caving mining infrastructure, and a data medium.

TECHNICAL FIELD

The present invention relates to a method for mining ore from an ore body. The present invention also relates to a mining infrastructure, a machinery, a monitoring system, an automatic or semi-automatic control system of a mining infrastructure, and a data medium.

BACKGROUND

In a massive deposit, caving methods rely on naturally or induced rock mass failure either by means of gravity, prevailing stresses, or a combination of both. Caving causes overlying material to fall into a stope.

In prior art caving methods, such as block caving and variations thereof, the ore body is undercut thereby initiating caving of ore body, whereas in sublevel caving ore bodies too competent for caving have to be mined by means of drilling and blasting.

In all caving methods hangingwall rock mass is allowed to cave as mining advances with cave initiation and continuous propagation being easier to achieve in weak rock masses and/or low primary stress conditions. In addition, in cave mines, which are operated at relatively shallow depths, the stress magnitudes around active infrastructure can be handled.

Nevertheless, starting in late 1990s cave mining progressed to greater depths and more competent rock masses. As the stress magnitudes increase, caving is more difficult to realize and more rock pressure related issues are faced. Problems experienced comprise amongst other difficulties in cave initiation, ensuring continuous cave propagation, production level instability during undercutting, production or mining induced seismicity and associated rock burst damage. In a worst-case scenario, these issues could result in major economic losses or unplanned termination of the operation.

Furthermore, rock mechanical models and mining experience show that extreme abutment stresses develop around an undercut in block caving and variants thereof before and after initiation of continuous caving, and around active sublevels in sublevel caving. The high abutment stress magnitudes are critical and could damage undercut and production infrastructure, adversely affect rock mass properties in the future production level, or trigger damaging seismic events. Prior art approaches against abutment stresses are for example certain undercutting strategies minimizing pre-developed infrastructure in abutments or pre-conditioning methods for reducing abutment stress magnitudes. However, the trend to caving of more competent rock masses calls for larger undercut areas, but this again results in higher abutment stress magnitudes and higher seismic energy release. The issues mentioned above jeopardize the application of prior art caving methods at greater depths. In prior art caving methods, the high stresses and mining induced seismicity at great depths are a constant safety, production, and economic risk.

SUMMARY OF THE INVENTION

In view of prior art mining methods, it would be desirable to achieve a mining method for mining ore from an ore body, which solves or alleviates some of the drawbacks of the prior art.

Therefore, one object of the invention is to provide a method for mining ore from an ore body which addresses critical rock mechanical issues and provides safety and protection for mining infrastructure when cave mining in deep, massive ore bodies.

Another object of the invention is to provide a method for mining ore from an ore body which enables large scale, low cost cave mining in deep, massive ore bodies.

These or at least one of said objects is achieved by a Raise Caving mining method for mining of ore from an ore body wherein further embodiments are incorporated in the dependent claims.

Hence according to one aspect, the present invention relates to a Raise Caving mining method for mining ore from an ore body is provided which comprises the steps:

Developing at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise within the rock mass providing the favourable stress environment, progressing upwards by mining at least one production stope from the at least one production raise, and drawing ore from the production stope.

The mining method according to the present invention, herein also referred to as Raise Caving mining method, enables large scale, efficient cave mining in massive ore bodies at great depths due to provision of favourable stress environment, where the problems related to rock mechanics are reduced, such that the overall rock pressure situation can be managed. Consequently, less extensive and expensive support is required, rock burst and associated safety risk is reduced significantly, and overall economic risk is lower. Moreover, the Raise Caving mining method may also be implemented at shallow depths.

In order to address critical rock mechanical issues in prior art caving methods, the present invention relies on de-stressing of rock mass with minimum amount of infrastructure by application of de-stressing slots and pillars, placing of production infrastructure in the rock mass that provides a favourable stress environment, and extracting of ore from the ore body located in that rock mass. Furthermore, by means of applying an advantageous mining sequence the favourable stress environment can be provided in the active mining area.

The inventors of the present invention conducted a study aiming to investigate the application potential of Raise Caving from a rock mechanics point of view and to outline effects on safety, productivity and potential for automation. Study results yield that the present invention, the Raise Caving mining method, is applicable from a rock mechanics point of view and that Raise Caving mining method seems to offer considerable advantages compared to existing caving methods. The following general improvements offered by the novel Raise Caving mining method are outlined. The outline is valid for all prior art caving methods. However, specific emphasis is put on sublevel caving, which has been the main mining method used in the mining company throughout the years. However, there are also inherent problems in sublevel caving, which will be addressed by the novel Raise Caving mining method.

Each slot generates a stress-shadow at certain locations adjacent to the slot. Said stress-shadow de-stresses the rock mass thereby creating the favourable stress environment in the vicinity of the slot. The stress-shadow also extends in the vicinity of the slots, both in the vertical and the horizontal direction, but the size and distribution of the stress-shadow may vary. Depending on prevailing ore body shapes, stress situation etc. the stress-shadow may have a varying size and shape, and may also vary over time, depending on mining layout and sequence. In this specification, the slots are also referred to as a de-stressing slots, emphasizing their purpose.

Therefore, it is advantageous to arrange and develop the production infrastructure in the de-stressed rock mass near the slots to ensure that the production infrastructure is protected. Thus, said production raise is preferably developed in the favourable stress environment created at certain locations adjacent said slots.

According to the method at least two slots are developed in the rock mass, a pillar which is part of the rock mass is left to separate the slots. Leaving a pillar between the slots generates a favourable stress environment for the further development of the said two slots in vertical direction and for the further development of the following slots located at a distance in the horizontal direction. The pillar controls stress magnitude in the rock mass at the position in the rock mass where the next slot will subsequently be developed, thereby creating a favourable stress environment to enable development of the next following slot.

In one form of the invention, the method comprises a step of implementing a mining sequence for providing the favourable stress environment in an active mining area. The mining sequence is a means for controlling mining induced seismicity in the active mining area.

In another form of the invention, the method comprises a step of implementing a mining layout for providing the favourable stress environment in an active mining area. The mining layout is a means for controlling mining induced seismicity in the active mining area.

In one form of the invention the method comprises a step of developing at least one slot raise from a drift arranged on a slot access level upwards to a drift arranged above the slot access level in the rock mass. Preferably the slot raise is developed at a distance from previous developed slot or slots or at a distance from previous developed slot raise or slot raises. The distance is determined by circumstances such as ore body shape, rock mass conditions, stress magnitudes and mining directions. Preferably the slot raise is developed by well-known processes and equipment.

In one form of the invention, the method comprises that at least one of said slots is developed from said at least one slot raise by blasting upwards from the drift arranged on the slot access level to the drift arranged above the slot access level.

In one form of the invention, the method comprises that at least one of said slots is arranged in a contact area between the ore body and the surrounding rock mass formations. However, in another form of the invention, the method comprises that at least one of said slots is arranged inside the ore body. Thus, a part of the ore body is located between the slot and the surrounding rock mass formation. In yet another form of the invention, the method comprises that at least one of said slots is arranged outside the ore body. Thus, the positioning of the slots depends on ore body shape, rock mass conditions, stress magnitudes, and mining directions.

In one form of the invention, the method comprises that at least one of said slots is oriented in vertical direction. In another form of the invention at least one of said slots is oriented in inclined direction. However, the slot does not have to be oriented in the dip direction of the ore body. Thus, the longitudinal axis of the slot may be oriented in vertical or inclined direction. By inclined is meant that the slot is directed at least 40 degrees from the horizontal plane. The orientation of the slots depends for example on the geometry of the ore body. Thus, in one form of the invention, the method comprises that adjacent slots are oriented in different directions.

In one form of the invention, the method comprises a de-stressing phase for generating and expanding the favourable stress environment in the rock mass, to protect mining infrastructure, in particular the production infrastructure in the production area, and a production phase for extraction of ore from the ore body, and wherein the de-stressing phase and the production phase are integrated such that in a certain mining area the production phase benefits from the de-stressing phase.

Although both phases have different purposes, they cannot be individual, independent phases. Rather both phases must be designed together to form a functionally integrated and applicable Raise Caving mining method. The two phases require different type of infrastructure. Infrastructure required for the de-stressing phase is herein referred to as de-stressing infrastructure. Infrastructure required for stoping is herein referred to as production infrastructure. The amount of infrastructure for development of slots in the de-stressing phase can be kept to a minimum, which is advantageous in that costs can be reduced. Moreover, this implies also that less de-stressing infrastructure is exposed to high stresses and associated costs for rock support and possible rehabilitation. The mining infrastructure comprises both de-stressing infrastructure and production infrastructure.

In one form of the invention the method comprises a step of developing at least one start-slot from the slot access level to a predetermined vertical extent to generate a stress-shadow to provide protection for production infrastructure located above the slot access level and adjacent to the start-slot.

In one form of the invention the method comprises that the start-slot is developed from at least one slot raise by blasting upwards along the slot raise from the drift arranged on the slot access level to the predetermined vertical extent. It is advantageous to develop the start-slot from a slot raise, since the machinery and equipment for developing the start-slot can be located in the slot raise and operated from there.

In one form of the invention the method comprises a step of developing a continuous start-slot from at least two start-slots in order to generate a stress-shadow S to provide protection for production infrastructure located above the slot access level and adjacent to the start-slot. The continuous start-slot is formed by joining at least two adjacently arranged start-slots to a continuous start-slot. This is advantageous in that the continuous start-slot generates a stress-shadow which provides protection for production infrastructure such as drawpoints, arranged adjacent the start-slots. Furthermore, the infrastructure on a draw level may be protected from exposure to high stress by the continuous start-slot. The vertical extent of the start-slot depends on for example rock mechanics and rock mass conditions, but the vertical extent is adapted such that the area of infrastructure on the draw level is appropriately and sufficiently de-stressed.

In one form of the invention the method comprises a step of developing at least one of the slots from the roof of at least one start-slot to the raise level arranged above the slot access level, wherein the roof area of the slot is smaller than the roof area of the start-slot. Thus, the slot is developed as a continuation of the start-slot. In particular, the cross-sectional area perpendicular to the longitudinal axis of the slot is smaller than the cross-sectional area of the start-slot perpendicular to its longitudinal axis. Preferably, the start-slot and the slot are configured to have similar thickness.

In one form of the invention, the method comprises a step of developing a slot access level in the rock mass. The slot access level, arranged below the draw level, is the level where the slots/start-slots begin. The slot access level may also be provided with slot drawpoints and drifts for drawing swell during start-slot and slot development. A drawpoint is the excavated structure, through which the caved or broken ore is loaded and removed from the start-slot, slot or stope.

In one form of the invention, the method comprises a step of developing the draw level located in a favourable stress environment. Typically, the draw level is developed in the rock mass above the slot access level. Preferably production infrastructure is developed at the draw level and in a stress-shadow provided by at least one of said slots and/or at least one of said start-slots.

In one form of the invention, the method comprises developing at least one further draw level located in a favourable stress environment. Several draw levels may be provided to enable efficient drawing of ore from the stopes. In one form of the invention, the method comprises that the draw level comprises draw infrastructure such as slot drawpoints, stope drawpoints, drifts.

In one form of the invention the drawpoints may be long-term and stationary. This is advantageous in that automation in mining is facilitated.

In one form of the invention, the method comprises a step of developing slot drawpoints into the slots and/or start-slots at the draw level. The draw of broken rock mass in slots and start-slots can either be done from the slot access level, the draw level or for example raise levels arranged above the slot access level.

After slot development has de-stressed the region of the rock mass where the draw level is arranged, slot drawpoints may be installed at the main draw level. Thereafter the slot access level is no longer required and may be abandoned.

In one form of the invention, the method comprises that the production stope generates a favourable stress environment which protects production infrastructure in the vicinity of the production stope. This is advantageous in that further production infrastructure such as drifts, raises, drawpoints, or rock passes can be safely installed next to the production stope in a favourable stress environment.

During the production process of the mining operation several production stopes may be developed next to each other. In one form of the invention, the method comprises that the interaction of two or more production stapes generates a regional favourable stress environment for protection of mining infrastructure. Preferably, the progressing production process results in an increasing extent of the regional favourable stress environment in the rock mass such that the mining infrastructure can be stepwise developed according to production progress and the mining infrastructure can benefit from the regional favourable stress environment.

In one form of the invention, the method comprises a step of developing an intermediate draw level where required, to improve extraction of ore from the stope. If the ore flow to the draw level cannot be ensured due to ore body shape or ore body inclination, the development of one or more intermediate draw levels may become necessary. The intermediate draw levels may be developed on the raise levels.

In one form of the invention, the method comprises a step of developing stope drawpoints into the production stopes from one or more intermediate draw levels after a production stope roof has advanced beyond the intermediate draw level. This is advantageous in that ore from the production stope may be drawn on several levels.

In one form of the invention, the method comprises a step of delayed development of at least one rock pass where required, in between an intermediate draw level and another level below the said intermediate draw level. Preferably the rock pass is developed in favourable stress environment created by at least one production stope. By delayed development is meant that the rock pass is developed after a production stope roof has advanced beyond the said intermediate draw level.

In one form of the invention, the method comprises a step of delayed development of at least one horizontal or inclined haulage tunnel where required. The inclined haulage tunnel extends between an intermediate draw level and another level below or above the intermediate draw level. The inclined haulage tunnel may be located in favourable stress environment created by at least one production stope.

In one form of the invention, the method comprises a step of mining the production stope by drilling and blasting. In another form of the invention the method comprises a step of mining the production stope by caving.

In one form of the invention, the method comprises a step of developing at least one slot from a drift arranged on a first sublevel by means of upwards drilling and blasting rounds to a drift arranged on a second sublevel arranged above the first sublevel in the rock mass, and blasting and loading said rounds in a retreat manner.

In one form of the invention, the method comprises a step of extracting a pillar. Preferably said pillar is extracted by weakening the pillar actively by drilling and blasting from at least one production raise. Alternatively, said pillar is extracted by degrading the pillar strength by decreasing the pillar width-to-height ratio due to nearby stope mining and facilitating pillar yielding and self-destruction. Moreover, the pillar may de-stress because of pillar yielding and self-destruction.

In one form of the invention, the method comprises a step of extracting a de-stressed pillar by arranging a production raise in or near the de-stressed pillar.

In one form of the invention, the method comprises a step of extracting a pillar by means of caving.

In one form of the invention, the method comprises a step of extracting a pillar by means of drilling and blasting.

In one form of the invention, the method comprises a step of preventing premature caving of hangingwall due to presence of broken rock mass in the slots and stapes, pillars and implementing draw strategies.

In one form of the invention, the method comprises a step of connecting at least one production stope to previously caved masses thereby allowing previously caved masses to fill up the production stope.

In one form of the invention, the method comprises a step of caving parts of the hangingwall, to fill up at least a part of at least one mined out production stope.

In one form of the invention, the method comprises a step of caving the hangingwall facilitated by extraction of pillars thereby removing the hangingwall support provided by the pillars.

In one form of the invention, the method comprises a step of caving of the ore body between the overhand side of the slot wall and the hangingwall, wherein caving is caused by extraction of the pillars.

In one form of the invention, the method comprises a step of developing a slot from a raise, where the raise is not located inside the slot. This is advantageous for example in case a slot is blocked, whereby a raise located outside the blocked slot can be used for drilling and blasting inside the slot in order to clear the said blockage.

In one form of the invention, the method comprises a step of implementing at least one slot for de-stressing rock mass and protecting critical infrastructure in another mining method.

In one form of the invention, the method comprises that the mining geometry is adapted to and determined by production and/or ore body geometry.

In one form of the invention, the method comprises that the mining sequence is adapted to and determined by production and/or ore body geometry and/or rock mechanics consideration thereby controlling mining induced seismicity and high stresses.

In one form of the invention, the method comprises that the mine layout, infrastructure position and mining sequence can be adapted on short notice.

In one form of the invention, the method comprises that the mining sequence comprises development of the slot ahead of development of the respective production stope where the roof of the slot is a predetermined vertical distance ahead of the roof of the production stope, to ensure that the production stope is mined in rock mass located within favourable stress environment.

Preferably the stoping commences when the favourable stress environment has been generated. Thus, the development of a part of the slot should be made prior to developing the corresponding stope.

In one form of the invention the method comprises a step of monitoring the production stope via the production raise. Such monitoring may be performed by monitoring means arranged inside the production raise.

In one form of the invention the method comprises a step of monitoring the slot and/or start-slot via the slot raise. Such monitoring may be performed by monitoring means arranged inside the slot raise.

In one form of the invention the method comprises a step of controlling risk of air blast and cave stall in the production stope via the production raise. Such controlling may be performed by controlling means arranged inside the production raise.

In one form of the invention, the method comprises repeating the steps of the method to a larger area in the rock mass, to exploit the ore body in a safe manner.

In one form of the invention the method comprises a step of backfilling parts of the production stope.

In one form of the invention the method comprises the production of backfill material by mining designated excavations in waste rock. This could be achieved either by increasing a stope in vertical extent or producing separate stopes with the only purpose to produce waste for backfill to e.g. reduce surface deformations.

In one form of the invention, the method comprises a step of continuation of development of at least one of the previously developed slot raises upwards in the rock mass from the current level to a further level located higher up in the rock mass.

In one form of the invention, the method comprises a step of continuation of development of at least one of the previously developed slots by blasting upwards from the slot raise towards a further level located higher up in the rock mass.

In one form of the invention, the method comprises a step of continuation of developing at least one of said production raises upwards towards a further level in the de-stressed rock mass.

In one form of the invention, the method comprises a step of continuation of mining at least one of the production stopes upwards from the production raise towards a further level and drawing ore from the production stope via the draw level and/or an intermediate level.

In one form of the invention, the method comprises a step of leaving a temporary pillar arranged in between the production stope and the slot that is located adjacent the production stope.

In another form of the invention, the method comprises a step of leaving a temporary pillar in between adjacent production stopes.

Furthermore, certain elements of Raise Caving mining method could be applied in other ways. For example, de-stressing slots developed by raises could be applied as a de-stressing element in existing mining methods or for de-stressing and protection of critical long-term infrastructure. Moreover, neighboring stopes mined by raises could also replace a traditional undercut in block and panel caving. In this case, the size of the stope roof would be increased, until caving is initiated. Thus, raises equipped with appropriate machinery above an active cave would provide possibilities for pre-conditioning, cave advance monitoring, facilitating cave advance and steering of caving front.

In summary, the Raise Caving mining method according to the invention may preferably be realized in a rock mass with an ore body which is massive and located at shallow depth or great depth.

It should be noted that great depths refer to depths where the ratio of primary rock stress to uniaxial compressive strength (UCS) exceeds 0.4. Massive ore bodies are large in all directions and may be of any shape or size, also thick tabular shaped ore bodies are considered massive. As the ore body shape may vary, the main draw level, the raise levels, the slot access level and the intermediate draw level may be situated on different depths.

In prior art caving methods, seismicity occurs often near active infrastructure causing considerable damage. In contrast to prior art caving methods, only a very small amount of active infrastructure is required in seismically active areas when using the Raise Caving mining method according to the invention. The method is thus advantageous in that seismic energy may be released distant from most of the active infrastructure, i.e. drifts, drawpoints, raises, ore and rock passes, shafts etc. of various size and geometry, which are necessary to gain access to the ore body and to prepare the ore body for extraction.

In particular, prior art sublevel caving is known for long lead times of developments of sublevels. Such development is associated with high upfront capital cost. In addition, the built infrastructure is also vulnerable to stress and rock burst damage prior to its actual use.

Moreover, there is limited knowledge regarding prevailing and rock mass conditions at the time of development. In contrast thereto, the Raise Caving mining method according to the invention requires only a very small amount of infrastructure being developed upfront. Thus, most of the infrastructure is created just-in-time reducing upfront capital cost drastically and decreasing exposure time to high stress conditions. Additionally, short-term changes in the mine layout to react on encountered conditions are easily implementable. For example, placing infrastructure in difficult ground conditions can be avoided, designing of specific mine layouts and mining sequences in critical areas is possible or blasting work can be adapted to local conditions easily.

Thus, the Raise Caving mining method according to the invention is particularly advantageous in that it allows for adaptions in mine layout and/or mining sequence. Thereby, it is possible to improve the control of seismicity and/or high stresses and/or to improve infrastructure stability. In addition, such adaptions may further be implemented on short notice as well.

In prior art sublevel caving, conditions and excavation geometries of workplaces are very variable. Workplaces and activities are spread over numerous sublevels. For this reason, only a limited degree of automation could be realized so far in key processes related to development, rock breaking and mucking.

In contrast, the Raise Caving mining method requires significantly less development on a few levels only. Moreover, geometries of raises are very well defined and repetitively used throughout. Accordingly, currently faced issues in automation, such as positioning of machinery or drill hole detection, can be overcome. Additionally, drawpoints in Raise Caving are long-term and stationary. Subsequently, a Raise Caving operation is comparable to an “underground rock factory”.

The Raise caving mining method according to the present invention is advantageous in that it offers significant automation potential in the actual stoping process.

Furthermore, in prior art sublevel caving numerous closely spaced drawpoints are required on every sublevel. Comparatively, only a small amount of ore can be recovered from each drawpoint, before the drawpoint must be closed and the next one must be opened. The lifetime of a drawpoint is typically in the range of days. Production blasting takes place at the position of drawpoints as well, possibly causing drawpoint damage. Moreover, these drawpoints and associated infrastructure are always situated below the mined-out area in a stressed and seismically active zone.

In contrast to sublevel caving, in the Raise Caving mining method according to the invention developed drawpoints are used over many month or years. Furthermore, blasting and/or cave initiation is realized using production raises. Every production raise and associated de-stressing infrastructure utilize large deposit volumes. As a result, the required infrastructure amount may be reduced by 50% or even more compared to prior art sublevel caving. Accordingly, the required number of machinery and the required amount of consumables, such as explosives, rock support or energy, are reduced significantly. Subsequently inherent nitrogen losses from drift development blasting are reduced substantially. Additionally, drawpoints and production infrastructure are arranged in de-stressed rock mass.

Consequently, the Raise Caving mining method according to the present invention decreases infrastructure development efforts considerably and enables the majority of infrastructure to be situated in de-stressed areas.

Furthermore, in prior art sublevel caving every blast ring acts independently. The fragmentation and gravity flow are heavily influenced by the initial blast conditions (blast confinement, chargeability, drill deviation etc.). Hence, there are also great variations in the performance expressed in extraction figures, such as dilution, recovery and the occurrence of hang-ups.

In contrast to sublevel caving, in the Raise Caving mining method a free-face blasting situation prevails. Accordingly, a lower specific charge concentration can be used. Substantial secondary fragmentation effects can be expected, as the material falls into the stope and draw columns are high. Based upon the improved fragmentation, the probability of hang-ups is also reduced greatly.

Therefore, the Raise Caving mining method according to the invention may furthermore enable improved fragmentation and reduce hang-up occurrence.

Moreover, in prior art sublevel caving, draw of ore takes place at many drawpoints, which are in operation over a rather short period and thus only a comparably small tonnage of ore is drawn from each drawpoint. The actual dilution mechanisms depend on various factors, such as compaction of cave masses, fragmentation, and porosity of the blasted sublevel caving ring.

However, in contrast to sublevel caving, in the present Raise Caving mining method, the high ore column protects against dilution, if good draw control practice is followed.

Thus, the Raise Caving mining method according to the present invention is advantageous in that improved controlling of dilution may be achieved.

Furthermore, in sublevel caving, hangingwall caving and associated surface subsidence areas (the lowering of the ground surface following underground mining) increase gradually with every mined sublevel, but the situation is different when using the Raise Caving mining method. When the mining method according to the present invention is applied mining commences from bottom to top and hangingwall caving is delayed due to presence of broken rock mass in the slots and stopes, pillars and applied draw strategies. Consequently, surface subsidence may occur at a later stage and the footprint may be smaller. Thus, the impact on environment may be reduced.

Therefore, another advantage with the Raise Caving mining method according to the present invention is that the footprint of surface deformations may be reduced.

These or at least one of said objects are achieved by a Raise Caving mining infrastructure configured for mining ore from an ore body according to claim 53, wherein further embodiments are incorporated in the dependent claims.

Hence, according to one aspect the present invention relates to a Raise Caving mining infrastructure comprising at least two slots in a rock mass; a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for the mining infrastructure; at least one production raise within the rock mass providing the favourable stress environment; at least one production stope progressed upwards by mining from the at least one production raise; and a transport device configured to draw ore from the production stope.

Alternatively, the slot is associated with a stress-shadow at certain locations adjacent to the slot, wherein said stress-shadow de-stresses the rock mass thereby creating said favourable stress environment.

Alternatively, at least one slot raise is developed from a drift arranged on a slot access level upwards to a drift arranged on a level arranged above the slot access level in the rock mass.

Alternatively, at least one of said slots is developed from said at least one slot raise by blasting upwards from the drift arranged on the slot access level to the drift arranged on the level arranged above the slot access level in the rock mass.

Alternatively, at least one start-slot is developed from a slot access level to a predetermined vertical extent, wherein the start-slot generates a stress-shadow S to provide protection for production infrastructure located above the slot access level. Alternatively, a continuous start-slot is developed by joining at least two start-slots. Alternatively, at least one of the slots is developed from the roof of one of the start-slots, wherein the area of the slot roof is smaller than the area of the start-slot roof. Alternatively, a draw level is developed in rock mass located in a favourable stress environment. Alternatively, the draw level comprises draw infrastructure such as slot drawpoints, stope drawpoints and drifts, wherein the drawpoints are configured to be long-term and stationary.

Alternatively, the hangingwall is caved in order to fill up at least a part of at least one mined out production stope. Alternatively, the pillar or pillars are extracted. Alternatively, the pillars are extracted to facilitate hangingwall caving. Alternatively, intermediate draw levels are developed in order to improve extraction of ore from the stope.

These or at least one of said objects are achieved by a monitoring system configured for monitoring a Raise Caving mining infrastructure configured for mining ore from an ore body according to claim 66, wherein further embodiments are incorporated in the dependent claims.

Hence, according to one aspect the present invention relates to a monitoring system configured for monitoring a Raise Caving mining infrastructure configured for mining ore from an ore body, which monitoring system comprising: monitoring means for monitoring development of at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots and; monitoring means for monitoring creation of a favourable stress environment in the rock mass to provide protection for mining infrastructure; and/or monitoring means for monitoring development of at least one production raise (6 a,6 b) within the rock mass providing the favourable stress environment, and/or monitoring means for monitoring mining progressing upwards at least one production stope from the at least one production raise, and/or monitoring means for monitoring at least one pillar; and/or monitoring means for monitoring draw of ore from the production stope.

Alternatively, the monitoring system is configured for monitoring seismicity and/or stress and/or deformations in the rock mass where the Raise Caving mining infrastructure is located.

Alternatively, the monitoring system is configured for monitoring seismicity and/or stress and/or deformations in the active mining area. Alternatively, the monitoring system is configured for monitoring interaction of the production stope and the pillars located adjacent the production stope. Alternatively, the monitoring system is configured for monitoring the shape of the excavations such as the at least one raise, the slots and the at least one stope. Alternatively, the monitoring system is configured for monitoring the conditions of the excavation such as stability and/or instability of said excavation. Alternatively, the monitoring system is configured for monitoring the conditions of the pillar such as fracture zones. Alternatively, the monitoring system is configured for monitoring the ore flow and/or broken rock mass inside the stope. Alternatively, the monitoring system is configured for monitoring the production stope via the production raise. Alternatively, the monitoring system is configured for monitoring the slot regarding for example stability/instability/shape/ore flow/broken rock mass.

These or at least one of said objects are achieved by a machinery comprising a drilling and/or charging device according to claim 76, wherein further embodiments are incorporated in the dependent claims.

Hence, according to one aspect the present invention relates to a machinery configured for; developing at least two slots in a rock mass; and/or developing a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for a mining infrastructure; and/or developing at least one production raise within the rock mass providing the favourable stress environment; and/or developing at least one production stope progressed upwards by mining from the at least one production raise; and/or drawing ore from the production stope by means of a transport device configured to draw ore from the production stope.

Alternatively, the machinery is configured for drilling and/or charging the rock mass from inside the raise. Alternatively, the drilling and/or charging device comprises a drilling bore and/or blast charging equipment configured to develop the at least one production stope progressed upwards by mining from the at least one production raise. Alternatively, the machinery is installed on a platform, which is configured to be moved by a shaft hoist system within the raise. Alternatively, the machinery is configured for hydrofracturing from inside the raise. Alternatively, the machinery is configured for pre-conditioning and/or pre-breaking from inside the raise. Alternatively, the machinery is configured for installing support and/or reinforcement from inside the raise. Alternatively, the machinery is configured for loading and transporting ore from the production stope by loaders and/or trucks loaders and/or continuous draw machinery with conveyors. Alternatively, the Raise Caving mining infrastructure comprises the monitoring system according to any of claims 66 to 75.

Alternatively, the Raise Caving mining infrastructure comprises the machinery according to any of claims 76 to 82.

These or at least one of said objects are achieved by an automatic or semi-automatic control system as claimed in claim 85 wherein further embodiments are incorporated in the dependent claims.

Hence, according to one aspect the present invention relates to an automatic or semi-automatic control system of a Raise Caving mining infrastructure according to any of claims 53 to 65, wherein the automatic or semi-automatic control system is electrically coupled to a control circuitry configured to control the method according to any of claims 1 to 52.

Alternatively, the automatic or semi-automatic control system is configured for draw control. Alternatively, the automatic or semi-automatic control system is configured for implementing the mining sequence. Alternatively, the automatic or semi-automatic control system is configured for implementing the mining layout. Alternatively, the automatic or semi-automatic control system is configured for implementing a draw strategy.

Alternatively, the automatic or semi-automatic control system is configured for controlling that the method steps according to claims 1 to 52 are repeated to a larger area in the rock mass.

Alternatively, the automatic or semi-automatic control system comprises the machinery according to any of claims 76 to 82, wherein the machinery is configured to be operated by the automatic or semi-automatic control system in remote control mode and/or in automatic control mode and/or in semi-automatic control mode and/or manual control mode.

Alternatively, the automatic or semi-automatic control system comprises the monitoring system according to any of claims 66 to 75, wherein the monitoring system is configured to communicate with and be operated by the automatic or semi-automatic control system in remote control mode and/or in automatic control mode and/or in semi-automatic control mode and/or manual control mode.

Alternatively, The Raise Caving mining infrastructure comprises the automatic or semi-automatic control system according to any of claims 85 to 92.

These or at least one of said objects are achieved by a data medium as claimed in claim 94.

Hence, according to one aspect the present invention relates to a data medium, configured for storing a data program, configured for controlling the automatic or semi-automatic control system according to any of claims 85 to 92 and/or configured for controlling the machinery according to any of claims 76 to 82, and/or configured for controlling the monitoring system according to any of claims 66 to 75, said data medium comprises a program code readable by the control circuitry for performing the method according to any of claims 1 to 52 when the data medium is run on the control circuitry.

Above outlined one or more technical advantages achieved by the Raise Caving mining method, the Raise Caving mining infrastructure, the monitoring system, the machinery, automatic or semi-automatic control system of a Raise caving mining infrastructure and data medium according to the present invention may result in some or all of the following overall improvements compared to prior art caving methods.

-   -   Improving safety:         -   fewer workplaces, which need to be secured         -   high degree of automation         -   less infrastructure in highly stressed and seismically             active rock mass         -   reduced exposure of mine workers to high rock stresses and             thus less exposure to hazardous areas         -   standardized workplaces and procedures (underground rock             factory)         -   accessibility of stope (reduced risk for air blast, cave             stall etc.)     -   reducing mining costs significantly:         -   high degree of automation         -   provides better fragmentation and less hang-ups         -   requires markedly lower infrastructure development by about             50%         -   does not need large upfront infrastructure development         -   allows for faster ramp-up time         -   allows to place majority of infrastructure in de-stressed             rock mass         -   lower support and rehabilitation demand         -   delays and reduces needs for surface infrastructure             relocation (if necessary)         -   allows to increase production capacity due to less dilution         -   more predictable and stable production     -   providing better sustainability of the mining operation:         -   enables resource utilization at great depths         -   causes reduced consumable consumption and nitrogen losses         -   enables use of stationary, power line supported equipment         -   enables use of electrified equipment         -   requires smaller waste dumps due to less dilution         -   smaller surface subsidence footprint

In this specification the following terms and expressions are defined as below and are used accordingly.

The term “ore” refers to a mineral aggregate of sufficient value as to quality and quantity to be mined at a profit. The prevailing definition of ore does not only comprise metal ore, but any other mineral aggregates, for example industrial minerals etc.

The term “ore body” refers to a volume of rock mass containing ore. In this specification the term “deposit” is used synonymously for ore body.

“Hangingwall” is the term which describes the upper or overhanging wall of a deposit, ore body, excavation, stope, an inclined vein, fault, or other structure. The term “hangingwall stability” is used primarily to describe the rock conditions of the upper and overhanging walls of excavations from a stability point of view. In open stopes stable hangingwalls are required. In caving stopes the hangingwalls should fail. The critical parameters which determine hangingwall conditions are the strength and structure of the hangingwall rock mass and the dimensions and shape of the excavation. The expression “hangingwall caving” refers to progressive failure or caving of hangingwall rocks.

The term “underhand” refers to a part of the rock mass facing the footwall, and the term “overhand” refers to the part of the rock mass facing the hangingwall.

The term “slot” refers to a long tabular excavation with length and width which are several times greater than its height. The extension of the slot along its length is referred to as long axis and can be horizontal, vertical or inclined. The slot is a discontinuity in the rock mass which cannot transmit stresses acting normal on the slot surfaces. As a result, the volume of rock in the vicinity of the slot is de-stressed in the direction normal to the slot surface. The de-stressing effect in the rock mass diminishes with distance from the slot. De-stressing is greatest in the volume of rock behind the slot area defined by the length and width of the slot.

Furthermore, a “pillar” is that part of the rock mass left unmined to prevent rock displacement between opposing rock walls in an excavation. Horizontal pillars are known as sill pillars. Other pillars are named after their function, which could be either to support the excavations (support pillars) or to protect other mine infrastructure (protection pillars). Depending on the characteristics one can distinguish between a barrier pillar, a yielding pillar or a crush pillar. Thus, a “barrier pillar” refers to a large, massive pillar being able to withstand considerable loads”, a “yielding pillar” refers to a pillar which is designed to deform constantly under a certain load, and a “crush pillar” refers to a pillar which is designed to fail stable and reliably at a certain load.

The expression “favourable stress environment” refers to a stress state, which is controllable, and which does not require extensive and expensive support measures for subsequent operation in the respective mining area. A favourable stress environment could be either a de-stressed area in a rock mass, or an abutment area where abutment stresses are limited or restricted to a controllable magnitude. The favourable stress environment serves the purpose to create a favourable environment for the subsequently establishment of slot raises and slots in the mining area. It further facilitates the establishment of the production raise and the subsequent operation in the production stapes. The combination of the de-stressing slots and the production stapes create a favourable environment for the infrastructure in the vicinity of the production area.

The term “favourable stress situation” is used synonymously. From the above follows that the term “de-stressing” refers to the process of creating a de-stressed environment in the rock mass i.e. a stress-shadow.

The term “stress-shadow” refers to a part of the rock mass where the stress is reduced in at least one direction in comparison with the pre-mining rock stress in corresponding direction in the same part of the rock mass.

The term “raise” refers to a vertical or inclined mine infrastructure opening.

The term “rock pass” refers to steeply inclined passage-ways used for the transfer of material in underground mine workings. Rock passes are designed to utilize the gravitation potential between levels in order to minimize haulage distances and facilitate a more convenient material handling system. The term “ore pass” refers to rock passes that are solely used for the transport of ore. In deep mines it is common practice to gravitate the ore to the deepest level in the mine from where it is hoisted to surface. The terms “tunnel” and “drift” are herein used as synonyms and refer to same type of infrastructure.

The term “stope” refers to the part of the ore body, from which ore is currently being mined or broken by stoping.

The term “stoping” includes all, operations of breaking rock or mineral for example by drilling and blasting and/or caving, and extracting rock or mineral in stopes, subsequent to development.

“Active mining areas” are areas of significant and ongoing stress changes resulting from mining activities. These are predominately but not exclusively the extraction (stoping) areas. The heading of tunnels under development are also active areas but on a localized scale. Active mining areas require ongoing supervision, monitoring of ground conditions and attention to excavation support. As mining advances active areas change to passive areas which require reduced levels of supervision and monitoring with the exception of main transport and regularly used infrastructure excavations.

The expression “mining sequence” refers to the sequence of mining activities which should be followed in order to achieve the overall goals of extraction of the ore body as complete as possible, the safety and economy of the mining operation, considering operational factors, rock mechanical constraints and other factors.

The expression “drawpoint” refers to the excavated structure, through which the caved or broken ore is loaded and removed from the slot or stope.

The term “drawbell” refers to an excavated structure which channels caved or broken rock mass to at least one drawpoint.

The term “de-stressing infrastructure” refers to the infrastructure required in the de-stressing phase. The de-stressing infrastructure comprises amongst other tunnels, inclines and/or declines to slots and/or start-slots, slot raises or slot drawpoints. The de-stressing infrastructure is situated on several levels, for example on raise levels or main draw level.

The term “production infrastructure” refers to the infrastructure required for the extraction of the ore body during the production phase. The production infrastructure comprises amongst others draw levels, stope drawpoints, tunnels, cross-cuts, production raises, ore passes and/or rock passes. The production infrastructure may be situated on several levels, for example draw level or intermediate draw levels.

The term “mining infrastructure” comprises both de-stressing infrastructure and production infrastructure. The term “main infrastructure” refers to the long-term infrastructure, which is required throughout the life of mine for the purpose of gaining access to the ore body. The main infrastructure comprises amongst others main shafts, main ramps, service excavations, main transportation tunnels from extraction area to main shafts or main ramps or ventilation raises.

In this specification the term “slot access level” should be understood as a level in the rock mass which is suitable to function as a starting level for developing start-slots and/or slots in the Raise Caving mining method.

The term “pre-conditioning” refers to a technique to increase the in-situ fragmentation of the rock mass so that it will cave or fragment more readily.

The term “pre-break” refers to a technique which may be specifically used in a competent zone to re-initiate caving to progress through this zone with the stope.

Furthermore, in specification the expressions “develop” and “developing” should be considered as broad terms and the term “develop” should have the same meaning as the words provide/arrange, and the word “developing” should have the same meaning as the words providing/arranging.

Additional objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following details and through exercising the invention. Whereas examples of the invention are described below, it should be noted that the invention may not be restricted to the specific details described.

BRIEF DESCRIPTION OF DRAWINGS

In order to fully understand the present invention and further objects and advantages of it, the detailed description set out below should be read together with the accompanying drawings, in which the same references denote similar in the various figures, and in which:

FIG. 1(a)-(c) schematically illustrates the basic principle of stope development according to the invention.

FIG. 1(a) illustrates a platform lowered into a raise for drilling and charging activities,

FIG. 1(b) illustrates the platform stored at top in hoist frame for blasting,

FIG. 1(c) illustrates excavation after blasting with void filled due to swell.

FIG. 2 schematically illustrates one form of the Raise Caving method according to the invention showing a view of a horizontal cross-section of slots and associated stress environment developed in rock mass.

FIG. 3 schematically illustrates one form of the Raise Caving method according to the invention showing a view of a horizontal cross-section of slots, pillars and production stopes and associated stress environment developed in rock mass.

FIG. 4 a schematically illustrates an isometric view of one example of a tabular slot and a corresponding slot raise according to the invention.

FIG. 4 b schematically illustrates an isometric view of one example two tabular slots, corresponding slot raises and a pillar separating the slots according to the invention.

FIG. 4 c schematically illustrates an isometric view of one example of a de-stressing layout according to the invention wherein the tabular slots are vertical and oriented in the same direction.

FIG. 4 d schematically illustrates an isometric view of one example according to the invention wherein the de-stressing layout is such that tabular slots are inclined.

FIG. 4 e schematically illustrates an isometric view of one example according to the invention wherein the slots 401,402,403 are vertical and oriented in a different direction.

FIG. 4 f schematically illustrates an isometric view of one example according to the invention wherein each of the slots is inclined and oriented in a different direction.

FIG. 4 g schematically illustrates an isometric view of one example of a slot according to the invention wherein the slot is gradually changed in upwards direction.

FIG. 4 h schematically illustrates a horizontal cross-section of one example of slots according to the invention wherein the slots are located inside the ore body.

FIG. 4 i schematically illustrates a horizontal cross-section of one example of slots according to the invention wherein the slots are located outside the ore body but inside the hangingwall.

FIG. 4 j schematically illustrates a view of a horizontal cross-section of one example of slots according to the invention wherein the slots are located partially inside the ore body and partially inside the hangingwall.

FIG. 4 k schematically illustrates a view of a vertical cross-section of one form of the Raise Caving method according to the invention.

FIG. 4 l schematically illustrates a horizontal cross-section of one form of the Raise Caving mining method according to the invention.

FIG. 5 a schematically illustrate one example of de-stressing slots according to the invention.

FIG. 5 b schematically illustrate another example of de-stressing slots according to the invention.

FIG. 5 c schematically illustrate one example of de-stressing slots according to the invention.

FIG. 6 a schematically illustrates a view of one form of the method according to invention.

FIG. 6 b schematically illustrates a line drawing of a further development of the form of the method as shown in FIG. 6 a;

FIG. 7 a schematically illustrates a vertical cross-section of a lower part of the slot 3 a and start-slot 4 a illustrated in FIG. 6 a;

FIG. 7 b schematically illustrates a side view of the form of the method shown in FIG. 6 b;

FIG. 8 a schematically illustrates a view of another one form of the method according to invention showing further progress of de-stressing of the rock mass and initial preparation of the production phase.

FIG. 8 b schematically illustrates a line drawing of the form of the method as shown in FIG. 8 a.

FIG. 9 a schematically illustrates vertical cross-section a lower part of the slot 3 a and the start-slot 4 a illustrated in FIG. 8 b;

FIG. 9 b schematically illustrates a vertical cross-section of slot 3 a shown in FIG. 9 a.

FIG. 10 a schematically illustrates a view of steps of one form of the Raise Caving mining method according to the invention.

FIG. 10 b schematically illustrates a line drawing of a further development of the form of the Raise Caving mining method according to the invention as shown in FIG. 10 a.

FIG. 11 a schematically illustrates a lower part of a vertical side view through stope 13 a of the form of the Raise Caving mining method illustrated in FIG. 10 a.

FIG. 11 b schematically illustrates a lower part of a side view of stope 13 a of the view as illustrated in FIG. 10 b.

FIG. 12 schematically illustrates a mining infrastructure according to one example;

FIG. 13 illustrates a flowchart showing an exemplary raise caving mining method;

FIG. 14 illustrates a flowchart showing a further example of a raise caving mining method; and

FIG. 15 illustrates a control circuitry adapted to operate an automatic or semi-automatic control system of a Raise Caving mining infrastructure, which automatic or semi-automatic control system is configured to perform any exemplary raise caving mining method herein disclosed.

DETAILED DESCRIPTION OF FORMS AND EXAMPLES OF THE INVENTION

The Raise Caving mining method, the mine layout and the mining sequence, the Raise Caving mining infrastructure, the machinery, the monitoring system, the automatic or semi-automatic control system and the data medium will be described in the following with references to the figures.

Raises are the central element in the Raise Caving mining method according to the invention. The raises are used for development of production stopes and for extraction of ore in stopes in de-stressed rock mass. The raises are developed by means of conventional techniques. Preferably, raises are also used for development of the slots. However, the slots may also be developed by conventional techniques, such as drilling and blasting a slot from horizontal tunnels.

FIGS. 1 a, 1 b and 1 c illustrate in a vertical cross-section the basic principle of stope development and stope blasting from a raise with mining equipment located in the raise. FIG. 1 a illustrates schematically the development of a stope 100 by drilling and blasting carried out from the mining equipment positioned on a platform 102, which is moved with a shaft hoist system 104 inside a raise 106. The same method may also be used when developing a slot.

As shown in FIG. 1 a , a raise 106 has already been developed by conventional techniques. The platform 102 and hoist system 104 are installed after development of the raise 106 is finished. The stope 100 is blasted in subsequent slices in upwards direction. However, in another form of the invention, the stope may also be run in a caving mode. Thereby, the rock mass above the roof of the stope fractures due to prevailing stresses and forces and thus rock mass detaches from the stope roof and falls into the stope.

FIGS. 1 a and 1 b illustrate schematically blast holes 107 drilled at a distance to the existing stope roof. The blast holes 107 could be either horizontal as shown in FIGS. 1 a and 1 b or inclined to achieve a better toe breakage. After blast holes 107 are drilled and charged with explosives, the hoist platform 102 is retracted to the top and stored in a safe position so that damage to the platform 102 resulting from blasting is avoided.

FIG. 1 c illustrates schematically that blasted rock mass 108 falls into the stope 100, and that there must be enough free space to absorb the swell of fragmented rock resulting from blasting. Before the next blast holes can be fired, enough blasted rock mass must be drawn from the stope accordingly. However, only the swell is drawn out of the stope so that the formation of an air gap is avoided.

However, if the stope is run in caving mode, the caving rate determines the draw rate. Namely, the draw rate must not exceed the rate of caving. However, even in caving mode the stope can be accessed via the raise 106, so that the cave back and the muck can be monitored. Moreover, the raise 106 and installed machinery on the platform 102 can be used for conducting pre-conditioning and pre-breaking techniques.

Routine work on the platform 102 inside the raise 106 can be carried out remote controlled or automated. Repair and maintenance of machinery can be carried out at the top of the raise, when the platform 102 is retracted. Hence, presence of mining personnel in raises can be kept to a minimum for, e.g. routine raise inspections or special, irregularly occurring work, which cannot be done by installed machinery on the platform or which cannot be done by other separate machinery on the platform run remote controlled or automated. As presence of mining personnel might be required in raise 106 and as machinery in raise must be protected from potential rock falls, the raise must be kept stable. If rock mechanical conditions require raise support, support can be installed from the platform 102. The platform construction itself provides additional protection for miners and machinery. The raise 106 has preferably a circular cross-section, which is a smooth and simple excavation shape. The platform 102 can be positioned in vertical direction via the hoist system 104. The preferably circular cross-section and the vertical positioning via the hoist system enable easier drill hole detection and identification compared to irregular drift shapes in conventional mining situations. This drill hole detection is critical for automation. Moreover, the platform 102 could have several platform levels above each other, where different types of machinery can be installed. These platforms shall be modular, stackable and interchangeable for the purpose of quick insertion and changes of machinery or repair of machinery. This configuration also provides the possibility to parallelize work in the raise.

The Raise Caving mining method according to the invention relies on de-stressing of rock mass by application of de-stressing slots. De-stressing slots are developed with minimum amount of infrastructure, which is built in advance.

Infrastructure, in particular production infrastructure, is developed in the rock mass de-stressed by the slots such that ore body inside that rock mass can be extracted. Furthermore, by means of applying an advantageous mining sequence the favourable stress environment can be provided in the active mining area.

FIG. 2 schematically illustrates a horizontal cross-section of one form of the Raise Caving mining method according to the invention wherein the slots 201,202 are developed progressively upwards in vertical direction in rock mass 60 according to the invention and in particular the de-stressing of rock mass. The first slot 201 and the second slot 202 are separated by pillar 211, which has been left between the slots 201,202 to separate them. Slot 201 and 202 are filled with broken rock mass.

Each slot 201,202 generates a stress-shadow S at certain locations adjacent to the slot, which is illustrated with dashed lines on each side of the slot. The stress-shadow S de-stresses the rock mass, which creates a favourable stress environment.

Thus, the stress-shadow S provides a reduced stress in the rock mass in comparison with the stress, which would be prevailing without the de-stressing slot. However, the rock mass also exhibits an increased stress T located at each end of the slot 201,202. Furthermore, the pillar 211 provides control of the stress magnitude in the rock mass at the position where the next following slot (on the left or right side of the slots 201, 202 is developed and near slot roofs of slots 201 and 202 thereby creating a favourable stress environment to enable development of the next slot (on the left or right side of the slots 201,202 and further development of slots 201 and 202.

The actual distribution of the stress-shadow S and the favourable stress environment depend also on the prevailing rock mass conditions, primary stress magnitudes, directions, the mine layout and mining sequence. The stress-shadow S creates a favourable stress environment in the rock mass that provides protection for the mining infrastructure. Infrastructure, in particular production infrastructure, is developed in the rock mass, which is de-stressed by the slots such that extraction of the ore body in de-stressed rock mass is enabled.

FIG. 3 schematically illustrates a view of a horizontal cross-section of slots 301,302,303,304, stopes 351,352,353 developed progressively upwards in vertical direction in ore body 61 according to one form of the invention and in particular the de-stressing of rock mass at a later stage, where stopes 351,352,353 have already been mined. Slots 301,302,303,304 and stopes 351,352,353 are filled with broken rock mass. Slots 301,302,303,304 and stopes 351,352,353 were developed from slot raises and production raises, respectively. FIG. 3 shows the extent of the stress shadow S and the favourable stress environment in the rock mass created by the slots 301,302,303,304 and stopes 351,352,353 schematically. The actual distribution of the stress-shadow S and the favourable stress environment depend also on the prevailing rock mass conditions, primary stress magnitudes, directions, the mine layout, and mining sequence.

FIG. 3 illustrates that as stoping progresses and the extraction of production stopes 351,352,353 continues where most of the pillars 311,312 between the slots 301,302,303 are weakened and subsequently removed. Pillar 311 has been extracted as a step of the Raise Caving mining method since the stapes 351,353 have been mined. Between the slots 302,303 are located the remains of separating pillar 312. Pillar 312 is partly extracted on the left side 312 a and partly fractured and broken on the right side 312 b. Thus, the right side 312 b of pillar 312 is de-stressed. Pillar 313 separates the slots 303 and 304 in the ore body 61. Accordingly, pillar 313 provides control of stress magnitude near slot roofs of slots 303 and 304 thereby creating a favourable stress environment. Furthermore, pillar 313 enables the development of the next slot at the right side of slot 304 from slot raise 321 by controlling the stress magnitude at position of slot raise 321.

The extent of stress shadow S may vary throughout the mining process. To illustrate, the stress-shadow S is indicated as an area delimited by dashed line around the slots, pillars, and stopes. Extracting the stopes 351,352,353, extracting the pillar 311 and extracting (left side 312 a) and weakening (right side 312 b) of pillar 312 increase the size of stress shadow S near slots 301,302,303. In comparison, the stress shadow S near slot 304 is still significantly smaller. Accordingly, the stress shadow S is continuously extended throughout the mining process thereby generating a regional favourable stress environment. Based upon that, the production stopes also provide protection for further mining infrastructure situated in said stress shadow S. The stress-shadow S creates a favourable stress environment in the rock mass, which protects mining infrastructure such as for example the slot raises, production raises, ore passes, rock passes or stope drawpoints, from high stress and mining induced seismicity. The stepwise progression of the stoping progression and extraction of production stopes and development of further slots in FIG. 3 illustrates implementation of an example of a mining sequence providing the advantageous, favourable stress environment in the active mining area.

FIGS. 4 a to 4 l schematically illustrate various examples of arrangements of de-stressing slots that may be developed and used in the method according to the invention to achieve a favourable stress environment for the mining infrastructure. FIGS. 4 a to 4 l outline the flexibility and adaptability of the de-stressing slots according to rock mass environment, rock stress situation, ore body shape and dimensions and the mining sequence. Furthermore, also combinations of these examples may be used in the method according to the invention.

FIG. 4 a schematically illustrates an isometric view of one example of a tabular slot 401 and a corresponding slot raise 421 according to the invention. The slot has a main, central longitudinal axis A1, and a transverse axis A2 perpendicular to the longitudinal axis. The cross-section of the slot has two perpendicular axis A2 and A3, wherein A2 is longer than the A3, see FIG. 4 a . The slot may have an essentially rectangular cross-section or an elliptical cross-section. As an example, the dimensions of the slots shown in FIG. 4 a is approx. 50×10 m in direction of their axis A2 and A3. The references A1, A2, A3 for the axis are used in the further description of slots. The slots may have a tabular shape or other shapes.

FIG. 4 b schematically illustrates an isometric view of one example of two tabular slots 401,402, corresponding slot raises 421,422 and a pillar 411 separating the slots 401,402 according to the invention. The pillar has a main, central longitudinal axis P1, and a transverse axis P2 perpendicular to the longitudinal axis. The cross-section of the pillar has two perpendicular axis P2 and P3, see FIG. 4 b . As an example, the dimensions of the pillar shown in FIG. 4 b are approx. 50×10 m in direction of their axis P2 and P3. The references P1, P2, P3 for the axis of a pillar are used in the further description of pillars. The extension of the pillar in direction of axis P1 is referred to as the length of the pillar. The extension of the pillar in direction of transverse axis P2 is referred to as width of the pillar and the extension of the pillar in direction of axis P3 is referred to as height of the pillar.

FIG. 4 c schematically illustrates an isometric view of one example of a de-stressing layout according to the invention comprising three tabular slots 401,402,403 developed from three slot raises 421,422,423. The central longitudinal axis A1 of each of the slots 401,402,403 is oriented in vertical direction and the slot raises 421,422,423 are vertical. Moreover, the axis A2 of each of the slots 401,402,403 are oriented in the same direction and the longitudinal axis A1 of each of the slots 401,402,403 is in the same plane. Pillars 411,412 separate neighboring slots.

FIG. 4 d schematically illustrates an isometric view of another example according to the invention wherein the de-stressing layout is such that tabular slots 401,402,403 are inclined.

Thus, the longitudinal axis A1 of slots is directed at least 40 degrees from the horizontal plane. Slots 401,402,403 are developed from inclined slot raises 421,422,423 and pillars 411,412 separate neighboring slots. The axis A2 of the slots 401,402,403 is oriented in the same direction and the longitudinal axis A1 of each of the slots 401,402,403 is in the same plane.

FIG. 4 e schematically illustrates an isometric view of another example according to the invention wherein the de-stressing layout comprises three tabular slots 401,402,403 oriented in vertical direction developed from vertical slot raises 421,422,423, whereby in this case the axis A2 of each of the slots 401,402,403 is oriented in a different direction. Pillars 411,412 separate neighboring slots. Moreover, the longitudinal axis A1 of each of the slots 401,402,403 is not in the same plane.

FIG. 4 f schematically illustrates an isometric view of another example according to the invention wherein the de-stressing layout comprises three tabular slots 401,402,403 oriented in inclined direction developed from inclined slot raises 421,422,423, whereby in this case the axis A2 of each of the slots 401,402,403 is oriented in a different direction. Pillars 411,412 separate neighboring slots. Moreover, the longitudinal axis A1 of each of the slots 401,402,403 is not in the same plane.

FIG. 4 g schematically illustrates an isometric view of another example according to the invention wherein a slot 409 is developed from a slot raise 429. In this example, the orientation of the axis A2 of the slot is gradually changed as the slot is developed in upwards direction. Thus, the slot has a “helix-type shape”.

FIG. 4 h schematically illustrates a horizontal cross-section of one example according to the invention wherein slots 401,402,403 are developed progressively upwards in vertical direction. The slots 401,402,403 are located inside the ore body 61. Stress shadows S and high stress zones T are also indicated. The figure indicates that the slots 401,402,403 are filled with broken rock mass, as described above.

FIG. 4 i schematically illustrates a horizontal cross-section of another example according to the invention wherein slots 401,402,403 are developed progressively upwards in vertical direction. In this example the slots 401,402,403 are located outside the ore body 61 but inside the hangingwall 62. Stress shadows S and high stress zones T are also indicated.

FIG. 4 j schematically illustrates a view of a horizontal cross-section of another example according to the invention wherein slots 401,402,403 are developed progressively upwards in vertical direction. In this example the slots 401,402,403 are located partially inside the ore body 61 and partially inside the hangingwall 62. Stress shadows S and high stress zones T are also indicated.

FIG. 4 k schematically illustrates a view of a vertical cross-section of one form of the Raise Caving mining method according to the invention provided with raise levels 441,442,443, slot raise 421 and slots 401,402. The slot 401 is developed between raise level 441 and raise level 442. Slot 402 is under development by means of drilling and blasting in upwards direction from slot raise 421 between raise level 442 and raise level 443. Slots 401, 402 are adapted to local hangingwall 62 boundaries. Therefore slot 401 and 402 are offset in horizontal direction. Moreover, slot 401 and 402 have different inclinations. Additionally, it is shown that the vertical distance between raise levels 441 and 442 and raise levels 442 and 443 is different. FIG. 4 k outlines the adaptability and flexibility of the Raise Caving mine layout to local conditions.

FIG. 4 l schematically illustrates a horizontal cross-section of one form of the Raise Caving mining method according to the invention. The figure provides an overview of Raise Caving at one point in time after the slots 401,402,403,404 have been developed and the stopes 451,452,453 have been mined. The figure shows that the slots 401,402,403,404 and stopes 451,452,453 are filled with broken rock mass as described above. The figure shows the Raise Caving mining method in the production phase. In this example the slots 401,402,403,404 are developed at the contact of ore body 61 and hangingwall 62. The slots are located in the ore body 61 and/or in the hangingwall 62. Pillars 411,412,413 separate neighboring slots. Slot 401 provides a stress shadow S1 for the production raise 431. Compared with the stress shadow S2 adjacent to slots 402, 403, 404 and stopes 451,452,453 the stress shadow S1 adjacent slot 401 is relatively small. Thus, the production raise 431 must be close to the slot 401.

The figure shows that the stope 453 has been mined adjacent to slot 404, which provided a stress shadow and thus a favourable stress environment for the extraction of stope 453. Stope 451 has been mined adjacent to slot 403, which provided a stress shadow and thus a favourable stress environment for the extraction of stope 451. Furthermore, stope 452 was mined after extraction of stope 451 and adjacent to stope 451, which provided a stress shadow and thus a favourable stress environment for the extraction of stope 452. The shape of the stopes 451,452,453 is variable and can be adapted to local conditions and needs. For example, the stope shape is adapted such that stapes end at the contact of ore body 61 and footwall 63. Thus, the shape of the stopes are adapted to the shape of the ore body.

Moreover, one or several production raises may be used for developing one stope. Because of extraction of stopes 451, 453 the pillars 412,413 between the slots 402,403,404 are fractured and de-stressed. Accordingly, a stress shadow of regional extent has been created near slots 402,403,404 and near stopes 451,452,453. This regional stress shadow also extends significantly into the hangingwall 62 and footwall 63. The production raises 432,433 were developed inside the said regional stress shadow.

The production raise 431 is located in the center of the production stope. However, production raises may alternatively be located offset from the center of the production stope, as illustrated by production raises 432, 433. The position of the production raise can be freely selected provided that the raise is located in a de-stressed rock mass located in a favourable stress environment generated by at least one of de-stressing slots 401,402,403,404 and/or neighboring stopes 451,452,453. Furthermore, the production raise 431,432,433 may be inclined in relation to a horizontal plane, however the production raise may alternatively be vertically arranged.

Extraction of stopes is performed from production raises 432 and 433, but as shown in the figures, the stopes have not been extracted up to the horizontal cross-section as shown in FIG. 4 l.

Overall, the form of the method as illustrated in FIG. 4 l outlines the flexibility and adaptability of the Raise Caving mining method according to the invention. The skilled person realizes that the method enables that position, orientation, shape and size of the elements of the method, the slot raises, slots, pillars, production raises, stopes, as well as the mining sequence can be flexibly adapted to ore body geometry, stress situation and rock mass conditions provided that the advantageous effect that a favourable stress environment is achieved such that problems related to rock mechanics are reduced, and the overall rock pressure situation can be managed. Furthermore, the adaptations of these elements may be carried out on short notice.

FIGS. 5 a to 5 c illustrate schematically different arrangements of development of de-stressing slots according to the invention.

FIG. 5 a provides a schematic isometric view of a slot 501 developed from a slot raise 521 in upwards direction by means of drilling and blasting. The slot raise 521 is positioned in the center of slot 501. First, a slot raise 521 has been developed between raise levels 541,542,543.

The development of slot 501 starts at raise level 541. The raise level 541 comprises drifts 571 arranged in different directions and slot drawpoints 561. Drifts 571 provide access to slot drawpoints 561, which are used for drawing broken rock out of slot 501. The slot 501 is developed above another raise level 542, which comprises drifts 571 and slot drawpoints. The slot 501 will be further developed until raise level 543 and drifts 571 arranged at raise level 543 provide access to the slot raise 521, the platform 102 and the shaft hoist system 104 (not shown in figure).

In FIG. 5 a it is illustrated that the slot is developed from a raise 521 which is located along the central longitudinal axis A1 of the slot 501. However, the slot may alternatively be developed from a raise which is offset from the central longitudinal axis of the slot depending on the circumstances.

FIG. 5 b provides a schematic isometric view of another arrangement of development of a slot wherein a slot 501 is developed bottom-up by means of upwards drilling and blasting rounds in a retreat manner between sublevels 581,582,583,584,585.

Slot development 501 started between sublevels 581 and 582 and proceeded upwards subsequently. Sublevels comprise drifts 571 in different directions. After slot development passed by a sublevel, slot drawpoints 561 are developed for drawing broken rock mass from the slot. Moreover, sublevels comprise a drift 572 before blasting of slot 501. This drift 572 is oriented along axis A2 of slot 501 and is used for drilling and blasting of slot 501.

Alternatively the slot 501 may be developed bottom-up, by starting for example from a drift 572 on sublevel 582 by downwards drilling and blasting rounds to a drift located on sublevel 581 below. Thereafter drilling continues from level 583 downward to level 582. The development may be performed by ring blasting retreat or crater blasting techniques to mimic sequential blasting of slices. (Not shown in the figures).

Alternatively the slot 501 may be developed top-down, by starting for example from a drift 572 on sublevel 584 by upwards drilling to a drift located on sublevel 585 above, and thereafter continue by drilling from level 583 to 584.

FIG. 5 c schematically illustrates one example of a de-stressing slot according to the invention showing development of a slot 501. First, a slot raise 521 was developed between raise levels 541,542,543. The development of slot 501 started at raise level 541 subsequently. Raise level 541 comprises drifts 571 arranged in different directions and slot drawpoints 561. Drifts 571 provide access to slot drawpoints 561, which are used for drawing broken rock out of slot 501. The slot 501 has been developed above another raise level 542, which comprises drifts 571 and slot drawpoints.

FIG. 5 c shows that slot 501 could not be further developed from slot raise 521 in upwards directions for various reasons. Thus, as slot development cannot proceed, the slot roof 501R is stopped at a certain position. In order to commence the further slot development, another slot raise 522 is developed between raise levels 542 and 543. From said slot raise 522 drill holes 591 are drilled and charged with explosives above the slot roof 501R. Drill holes are subsequently fired in order to proceed with slot development. After the problem is resolved, further development of slot 501 may be conducted from slot raise 521 or slot raise 522.

In another form of the invention the slot raise 522 is used for drilling blast holes into the slot, which are subsequently blasted. This is particularly advantageous when there is a hang-up in the slot 501 due to broken rock or ore that is stuck. In such case drilling and blasting can be carried out from a slot raise 522 outside the slot.

FIGS. 6 a to 11 b illustrate schematically the overall concept of Raise Caving mining method according to the invention and show therefore the application of the Raise Caving mining method in a schematic ore body.

The Raise Caving mining method comprises different types of infrastructure, elements and levels for the de-stressing and production phase. It should be noted that for the purpose of illustration the figures show de-stressing and production infrastructure such as raises, slots, tunnels, drawpoints, rock passes or ore passes, stapes and levels arranged in the rock mass. However, for the purpose of illustration, some elements, such as the rock mass, ore body or pillars are indicated only by numbers in some of the figures such as 4 c-4 g, 4 k,6 a-b, 7 a-b, 8 a-b,9 a-b,10 a-b, 11 a-b.

The Raise Caving mining method can be divided into two phases, namely a de-stressing phase and a production phase. Preferably the mining method comprises a de-stressing phase for generating and expanding the favourable stress environment in the rock mass, in order to protect mining infrastructure and in particular the infrastructure in the production area, and a production phase for extraction of ore from the ore body, and wherein de-stressing phase and the production phase are integrated such that in a certain mining area the production phase benefits from the de-stressing phase. The de-stressing phase and production phase may be run in parallel.

FIG. 6 a schematically illustrates a view of one form of the method according to invention showing initial steps of the method. FIG. 6 b schematically illustrates a line drawing of a further development of the form of the method as shown in FIG. 6 a . FIG. 7 a schematically illustrates a vertical cross-section of a lower part of the view illustrated in FIG. 6 a and FIG. 7 b schematically illustrates a side view of the form of the method shown in FIG. 6 b.

FIG. 6 b shows a slot access level 2, slot raises 1 a,1 b,1 c, slot 3 a, start-slots 4 a, 4 b and raise levels 5.1, 5.2. FIG. 6 b shows that a slot access level 2 is developed in a rock mass. This slot access level 2 comprises drifts 28 giving access to the ore body 61 and especially preparing the development of start-slots 4 a,4 b and slot 3 a. In this form of the invention, the slot access level 2 is the lowermost level. A first slot raise 1 a is developed for example by a conventional raise boring method from a drift D1 arranged on the slot access level 2 and upwards to a drift D2 arranged on a first raise level 5.1 arranged above the slot access level 2 in the rock mass. The first slot raise 1 a is thereafter further developed to a drift D3 arranged on the second raise level 5.2 which is located above the first raise level 5.1 in the rock mass. The slot raise 1 a, and further slot raises 1 b,1 c, are developed in the same way, and may extend up to several hundred meters upwards. As shown in the figure, the development takes place in a stepwise manner.

In one form of the invention the method comprises that a start-slot 4 a and a slot 3 a are developed by drilling and blasting carried out from platform 102 (see FIG. 1 ) operating inside the slot raise 1 a. Blasting of the start-slot 4 a and slot 3 a is done from the bottom of the start-slot 4 a in upwards direction. A start-slot 4 a is developed from the slot raise 1 a in upwards direction by drilling and blasting from the drift D1 at the slot access level 2 to a predetermined vertical extent above the access level 2. The start-slot 4 a generates a stress shadow S in the vicinity of the start-slot 4 a which creates a favourable stress environment in the rock mass to provide protection for production infrastructure located above the slot access level 2 and adjacent to the start-slot 4 a.

The vertical extent of the start-slot 4 a is adapted such that the rock mass above the slot access level 2, where production infrastructure will be later developed, will be appropriately and sufficiently de-stressed. The production infrastructure will be developed in the vicinity of the start-slot 4 a on a further level located in the rock mass above the slot access level 2, preferably on a draw level developed in rock mass located in a favourable stress environment generated by start-slots and/or de-stressing slots.

In one form of the invention the draw level coincides with a main haulage level, where the main transportation system is installed. In such case the slot access level may also be referred to as main haulage level-1 since the slot access level is arranged below the main haulage level.

As illustrated in FIG. 6 b , the slot raise 1 a extends further upwards from the start-slot 4 a. The slot 3 a is developed upwards from the slot raise 1 a by drilling and blasting. The slot 3 a starts at the roof 4R of the start-slot 4 a and extends to the drift on the first raise level 5.1 arranged above the slot access level 2. The slot 3 a has a slot roof 3R. The cross-sectional area of the slot 3 a perpendicular to the longitudinal axis A1 of the slot is smaller than the cross-sectional area of the start-slot 4 a perpendicular to the longitudinal axis A1 of the start-slot. In particular, the width of the slot 3 a is smaller than the width of the start-slot 4 a. The width of the slot 3 a or start-slot 4 a is the extension of the slot 3 a or start-slot 4 a in direction of axis A2, respectively. As an example, the start-slots as described in the present method are approx. 100 m wide, and the slots are approx. 50 m wide. However, the slot and start-slot dimensions respectively depend on several parameters, such as the circumstances, the ore body shape or the stress situation at the location. Furthermore, slot drawpoints 21 are arranged on the slot access level 2 and developed into the start-slot 4 a to draw broken rock mass from the start-slot 4 a and slot 3 a.

Typically, the start-slot is located below the slot, however in another form of the invention a first de-stressing slot having a certain width is first developed from the slot raise by drilling and blasting in upwards direction from the drift arranged on the slot access level to a first predetermined vertical extent thereafter the width of the slot is increased such that a start-slot is developed from the slot raise by drilling and blasting in upwards direction from the roof of the slot (not shown in figures) to a second predetermined vertical extent. Thereafter, above the start-slot, a second de-stressing slot is developed from the slot raise by drilling and blasting in upwards direction from the roof of the start-slot towards the drift on a raise level.

In yet another form of the invention the start-slot begins from a draw level arranged above the slot access level and extend upwards to a predetermined vertical extent. Thereafter, a slot is developed upwards from the roof of the start-slot 4R towards a raise level (not shown in figures).

FIG. 6 b further shows that a second slot raise 1 b is developed from a drift arranged on the slot access level 2 and upwards to a drift D2 arranged on the raise level 5.1. The second slot raise 1 b is developed at a distance from the first slot raise 1 a. The distance is determined by circumstances such as ore body shape, rock mass conditions, stress situation and mining directions. Moreover, a second start-slot 4 b is under development from the second slot raise 1 b by drilling and blasting in upwards direction towards the drift D2 on the raise level 5.1. Slot drawpoints 21 are continued to be developed at the slot access level 2.

FIG. 6 b shows further that a continuous start-slot 20 is created by joining the two adjacent start-slots 4 a and 4 b. Thus, the start-slots 4 a and 4 b form the continuous start-slot 20 in order to generate a stress shadow S to provide protection by creating a favourable stress environment in the rock mass for the production infrastructure that will be developed above the slot access level 2 and in the vicinity of the continuous start-slot 20. As an example, the continuous start-slot 20 has a vertical extent of approximatively 100 m.

In another form of the invention, adjacent start-slots may be separated by an appropriately sized crush pillar. This crush pillar crushes due to prevailing stresses. Due to this crushing, the crush pillar de-stresses. As a consequence, the stress shadow is also present in the vicinity of de-stressed crush pillar. Thereby a persistent stress shadow is created in the vicinity of start-slots.

FIG. 6 b shows that the Raise Caving mining method comprises developing one or more raise levels 5.1, 5.2 arranged in the rock mass above the slot access level. The second raise level 5.2 is arranged above the first raise level 5.1 as illustrated in the figures. The vertical distance between the first raise level 5.1 and second raise level 5.2 is adapted to local needs and technical possibilities and may be up to 200 m to 300 m.

It should be noted that the references “first raise level” and “second raise level” only indicates the order of the raise levels that the slots and slot raises are developed to, and the position of each raise level relative to the slot access level. These raise levels do not preclude that additional drifts and/or levels are arranged in between the slot access level and the raise levels.

FIG. 6 b further shows that the slots 3 a and start-slots 4 a,4 b are inclined. By inclined is meant that the longitudinal axis A1 of slots and start-slots are directed at least 40 degrees from the horizontal plane. It should be noted that the axis A2 of slot and start-slots does not have to be oriented in strike direction of the ore body. Thus, the axis A2 of slot and start-slots may also be oriented out of strike direction of the ore body

The slots 3 a and start-slots 4 a,4 b generate a stress-shadow S at certain locations in the rock mass adjacent to the slot and start-slots in order to create a favourable stress environment to provide protection for mining infrastructure. Production infrastructure that is later developed in the favourable stress environment provided by the slot and start-slots is thereby protected from high stresses and seismic energy release. Thus, the de-stressing slot 3 a and start-slots 4 a,4 b substantially decrease or even prevent high stress and/or consequences of seismic energy releases in the part of the rock mass where the stress-shadow S is generated (not shown in this figure).

FIG. 8 a schematically illustrates a view of one form of the method according to invention showing further progress of de-stressing of the rock mass and initial preparation of the production phase. FIG. 8 b schematically illustrates a line drawing of the form of the method as shown in FIG. 8 a . FIG. 9 a schematically illustrates a vertical cross-section of a lower part of the view of the slot 3 a and the start-slot 4 a illustrated in FIG. 8 a and FIG. 9 b schematically illustrates a vertical cross-section of slot 3 a shown in FIG. 9 a . FIG. 6 b illustrates the de-stressing phase at an early stage of the Raise Caving method according to the invention, whereas FIG. 8 b illustrates a more advanced stage of the de-stressing phase, in which also some parts of production infrastructure have been developed.

The Raise Caving mining method for mining ore from an ore body 61 comprises at least two slots 3 a and 3 b developed in a rock mass. The slots 3 a, 3 b are placed next to the hangingwall 62 in FIG. 8 b . FIG. 8 b shows that the slots 3 a-3 b are developed from slot raises 1 a-1 b. Pillar 9 a separates neighbouring slots 3 a,3 b. Each slot raise is developed stepwise, in a first step the raise is developed from the slot access level 2 to a raise level 5.1, and then further to a raise level 5.2. Also, the slots 3 a,3 b are developed stepwise. The slot 3 a is developed from the first slot raise 1 a in upwards direction by drilling and blasting from the roof of the start-slot 4R to the raise level 5.1 and then further upwards towards the raise level 5.2 to ensure that the rock mass is de-stressed adjacent the slot 3 a and to provide a favourable stress environment for the subsequent development of production infrastructure adjacent to the slot 3 a.

The pillar 9 a is left between slots 3 a and 3 b. The pillar 9 a provides control of the stress magnitude in the rock mass at the position of slot raise 1 c, which is used for subsequent development of the next slot. Moreover, the pillar 9 a provides control of the stress magnitude near slot roofs of slots 3 a and 3 b. Thereby the pillar 9 a creates a favourable stress environment to enable further development of slots 3 a and 3 b and to enable development of the next slot from slot raise 1 c as well as the vertical extension of slot raise 1 c.

FIG. 8 b further illustrates that after the roof 3R of the de-stressing slot 3 a has advanced beyond a level, for example beyond raise level 5.1, this raise level 5.1 may be used for creation of additional slot drawpoints 21 into the slot 3 a thereby stimulating and facilitating rock flow in the slot.

FIG. 9 b shows a vertical cross-section of the slot 3 a and the start-slot 4 a and a draw level 8 with production infrastructure located in the ore body 61. The figure shows that the slot 3 a is developed in the contact area between the ore body 61 and the hangingwall 62.

As illustrated in FIG. 8 b , the start-slots 4 a-4 c are developed from the slot access level 2 to extend to a predetermined vertical extent above a draw level 8, which is located above the slot access level 2.

FIG. 8 b shows that a draw level 8 is developed and located in the favourable stress environment in the rock mass which is de-stressed by the start-slots and slots. The draw level 8 is developed in the de-stressed rock mass above the slot access level 2, this is advantageous in that the majority of long-term production infrastructure is situated at the draw level 8. The distance between the slot access level 2 and the draw level 8 depends on several factors, such as prevailing ore body shapes, stress situation and rock mass conditions.

As shown in FIGS. 8 b and 9 b the mining infrastructure at the slot access level 2 comprises drifts 28 and slot drawpoints 21 for drawing swell during development of start-slots and slots. The drawpoint 21,22 refers to the excavated structure, through which the caved or broken rock mass is loaded and removed from the slot or stope. After slot development has progressed upwards from the slot access level 2 and after the draw level 8 has been developed, slot drawpoints 21 may also be developed at the draw level 8. Thereafter the slot access level 2 is no longer required and may therefore be abandoned.

The slot drawpoints 21 are developed into the start-slots 4 a,4 b,4 c at the draw level 8. Furthermore, slot drawpoints 21 are also developed from the drifts 28 on the raise levels 5.1 into the slots 3 a,3 b to draw rock mass from the slots. However, in another form of the method according to the invention the slot drawpoints are not developed into the slots or start-slots.

The draw level 8 is developed and located in direct connection with the area where the production stope subsequently will be mined. The draw level 8 is used for extracting ore from the production stopes. The draw level 8 comprises draw infrastructure such as slot drawpoints 21, stope drawpoints 22 and drifts 28, wherein the stope drawpoints 22 may be long-term and stationary. The draw level layout is comparable to a draw level layout used in prior art block caving method, however the draw level 8 developed for the present method offers much more flexibility to configure drawbell shape and drawpoint arrangement (not shown in the figures).

The stopes mined by raises could also replace a traditional undercut in block and panel caving. In this case, the size of the stope roof would be increased, until caving is initiated. Thus, raises equipped with appropriate machinery above an active cave furthermore provide possibilities for pre-conditioning, cave advance monitoring, facilitating cave advance and steering of caving front.

The FIG. 8 b illustrates that the Raise Caving mining method further comprises a step of developing a production raise 6 a in the ore body 61 in the favourable stress environment created adjacent the slot 3 a and start-slot 4 a. The production raise is developed between a drift located on the draw level 8 and a drift on the raise level 5.1 by conventional methods, such as for example raise boring. The raise level 5.1 and the raise level 5.2 are then functioning as top levels of slot raises 1 a,1 b,1 c and production raise 6 a, respectively. The hoist system 104 (see FIG. 1 ) is installed at the top level of slot and production raises. Stope drawpoints 22 are developed on the draw level 8 adjacent the continuous start-slot 20.

FIG. 10 a schematically illustrates a view of one form of steps of the Raise Caving mining method according to the invention showing further de-stressing in order to create a favourable stress environment and advanced extraction of ore in the production phase and FIG. 10 b schematically illustrates a line drawing of a further development of the form shown in FIG. 10 a . FIG. 11 a schematically illustrates a lower part of a vertical side view through stope 13 a of the form of the Raise Caving mining method illustrated in FIG. 10 a and FIG. 11 b schematically illustrates a lower part of a side view of stope 13 a of the view as illustrated in FIG. 10 b.

As illustrated in FIG. 10 b the Raise Caving mining method comprises that pillars 9 a,9 b,9 c are left between the adjacent slots 3 a,3 b,3 c,3 d to separate adjacent slots. Each pillar is a piece of rock mass, which controls surrounding rock mass during the de-stressing phase and production phase. In the figures, for the purpose of illustration, the pillars are indicated as gaps between the slots 3 a,3 b,3 c,3 d and 3 a,3 b,3 c,3 d respectively. Each pillar 9 a,9 b,9 c controls stress magnitudes and seismicity around the de-stressing slots and provides control of stress magnitude in the rock mass at the position of the following slot thereby creating a favourable stress environment to enable development of the following slots. Thus, the pillar establishes a favourable stress environment for raise and slot development for the next de-stressing slot according to the mining sequence. As an example the distance between the center of two adjacently arranged slot raises 1 a,1 b,1 c,1 d may be approx. 100 m, thus leaving pillars 9 a,9 b,9 c which are approx. 50 m wide and 10 m high between adjacent slots, thereby separating the slots and providing a favourable stress environment for development of the next de-stressing slot. The width of the pillar is its extension in direction of axis P2 and the height of the pillar is its extension in direction of the axis P3.

The Raise Caving mining method is advantageous in that the amount of infrastructure required for the de-stressing phase is limited and rather small in comparison to the production phase.

FIG. 10 b shows that the Raise Caving mining method comprises a step of mining by progressing upwards the production stope 13 a from the production raise 6 a and a step of drawing ore from the production stope 13 a through stope drawpoints 22. The mining is carried out by drilling and blasting from the production raise. Also, production stapes 13 b and 13 c are mined in upwards direction by drilling and blasting in production raises 6 b,6 c. Moreover, FIG. 10 b shows that mining progresses upwards stepwise in the parts of the ore body that are de-stressed by the slots 3 a,3 b,3 c,3 d thereby provided with a favourable stress environment for protection of the production infrastructure. Each production raise 6 a,6 b,6 c is developed between a drift arranged on the draw level 8 stepwise to the raise levels 5.1,5.2 arranged above the draw level 8.

The actual mining of the production stope 13 a, 13 b, 13 c is typically carried out by drilling and blasting, where the drilling of drill holes and blasting the drill holes is carried out from the respective production raise 6 a,6 b,6 c. This is very advantageous in that safe and efficient stoping can be achieved, and the stoping can be carried out remotely controlled or automated. The blast holes 107 could be either horizontal as shown in FIG. 1 b or inclined to achieve a better breakage in blasting.

In another form of the method, the step of mining of the production stope 13 a-13 c is carried out by caving. The stope is typically run in drilling and blasting mode. However, a stope can also be excavated by means of caving.

FIG. 10 b shows that the slots 3 a,3 b,3 c have been developed above the stope roof of respective production stapes 13 a,13 b,13 c. Specifically, the slot roof 3R of slot 3 a has been developed above the stope roof 13R. Thereby slots 3 a,3 b,3 c provide a favourable stress environment for at least the production raises 6 a,6 b,6 c and production stopes 13 a,13 b,13 c.

FIG. 10 b shows that the production stope 13 a has been mined above the raise level 5.2. In order to stimulate ore flow in the stope intermediate draw levels 5.1,5.1.1,5.2,5.2.1 may be developed. Moreover, the installation of one or more intermediate draw levels 5.1,5.1.1,5.2,5.2.1 may become necessary, if the ore flow to the draw level 8 cannot be guaranteed due to ore body shape or ore body inclination.

In the form of the Raise Caving mining method shown in FIG. 10 b , the former raise levels 5.1 and 5.2 have partially been converted to intermediate draw levels 5.1 and 5.2 in areas where the stapes 13 a,13 b have been developed above the draw levels 5.1,5.2. Furthermore, additional intermediate draw levels 5.1.1 and 5.2.1 have been developed. Each intermediate draw level 5.1,5.1.1,5.2,5.2.1 is provided with at least one stope drawpoint 22. The production stope 13 a generates a stress-shadow S in the vicinity of the stope. Thus, a favourable stress environment is created which is advantageous in that it provides protection for further production infrastructure, such as intermediate draw levels 5.1,5.1.1,5.2,5.2.1 and ore pass 11 a. Preferably the intermediate draw levels 5.1,5.1.1,5.2,5.2.1 are developed after the stope roof 13R has advanced above planned position of respective intermediate draw levels 5.1,5.1.1,5.2,5.2.1 so that abutment stress damage to intermediate draw levels 5.1,5.1.1,5.2,5.2.1 and stope drawpoints 22 is prevented.

FIG. 10 b further illustrates rock passes 11 a and 11 b. Rock pass 11 a is developed between the draw level 8 and intermediate draw levels 5.1,5.1.1,5.2,5.2.1 in order to transport rock mass drawn from stope 13 a at stope drawpoints 22 arranged on the intermediate draw levels 5.1,5.1.1,5.2,5.2.1 to the draw level 8 below. The rock pass is a vertical or inclined excavation for transporting ore by means of gravity. The rock passes 11 a, 11 b, may be developed by means of for example raise boring and are used for transporting ore from intermediate draw levels 5.1,5.1.1,5.2,5.2.1 to the draw level 8. Rock passes 11 a, 11 b are developed at a later stage in the production phase in a favourable stress environment, which is generated by the adjacent production stopes 13 a,13 b. Preferably, the rock passes are developed stepwise together with the intermediate draw levels.

In another form of the invention, at least one rock pass 11 a, 11 b is developed delayed in between an intermediate draw level 5.1,5.1.1,5.2,5.2.1 and another receiving level arranged below the said intermediate draw level 5.1,5.1.1,5.2,5.2.1 in favourable stress environment created by at least one production stope 13 a,13 b. By delayed development is meant that the rock pass is developed subsequent to developing of the production stope.

The pillars provide initial support for the hangingwall. Thus, extraction of at least one of the pillars 9 a,9 b,9 c removes the support for the hangingwall 62, which causes the hangingwall 62 to cave. Thus, caved hangingwall masses fill up the stope. In the process of drawing a fully progressed stope, caved masses fill up the stope completely. FIG. 10 b shows that as the steps of stoping progress, also the pillars 9 a,9 b,9 c are extracted as part of the stoping process removing the temporary support from the hangingwall 62, which is provided by pillar 9 a,9 b,9 c. Preferably, the pillars 9 a,9 b,9 c are extracted by weakening each pillar actively by drilling and blasting from at least one production raise. In another form of the invention, the pillars 9 a,9 b,9 c are extracted by degrading the pillar strength by decreasing the pillar width-to-height ratio due to nearby stope mining and facilitating pillar yielding and self-destruction. The width of a pillar is its extension in the direction of axis P2 and the height of a pillar is its extension in the direction of axis P3. In one form of the invention, extraction of a pillar is achieved by arranging a production raise in or near the de-stressed pillar. In another form one form of the invention a pillar 9 a,9 b,9 c can be extracted by means of drilling and blasting or by means of caving.

In one form of the invention, only parts of the hangingwall 62 adjacent to the extracted pillar is allowed to cave in order to subsequently fill up the mined-out production stope adjacent to the extracted pillar.

In one form of the invention the method comprises a step of delaying hangingwall caving due to presence of broken rock mass in the at least one slot 3 a,3 b,3 c,3 d and/or in the at least one production stope 13 a,13 b,13 c, and/or presence of at least one pillar 9 a,9 b,9 c and/or implemented draw strategies. Thus, the broken rock inside the production stopes 13 a,13 b,13 c functions as a temporary hangingwall support and thus slows down caving of hangingwall 62 and dilution.

In another form of the invention, a stope is connected to previously caved masses, which start to flow into the stope as drawing of ore from the stope progresses.

It should be noted that in FIG. 10 b there are no pillars remaining between the stopes and slots, thus the stopes 13 a,13 b,13 c are developed adjacent to respective slot 3 a,3 b,3 c. However, in another form of the invention, the method comprises leaving a temporary pillar arranged in between the production stope and the respective slot that is located adjacent the production stope.

In FIG. 10 b there is no remaining pillar between the stopes 13 a-13 b. However, in another form of the invention the method comprises leaving a temporary pillar in between adjacent production stopes.

In another form of the invention, slots may be located inside the ore body such that a portion of the ore body is left between the slots and the hangingwall. Thus, extraction of at least one of the pillars causes caving of the ore body between the slot and the hangingwall.

The Raise Caving mining method is flexible and applicable to various ore body shapes and sizes. Main infrastructure such as hoists, main haulage drifts or workshops, are not shown in the figures for simplification. Outlined excavation dimensions and geometries are based on preliminary analysis and provide only a rough estimation of dimensions and geometries in the Raise Caving mining method according to the invention. The dimensions mentioned herein are only given as an example for the purpose of describing the invention and are not limiting to the invention. It is foreseen that the Raise Caving mining method may be applied at much larger scales than the given example. Geometries of slots, start-slots, stopes, drawpoints and draw levels can vary, because they are adapted to prevailing mining environment, which comprises amongst others the rock mass conditions, ore body shape and the stress situation.

For example, in the figures it is illustrated that the de-stressing slots 3 a,3 b,3 c,3 d the start-slots 4 a,4 b,4 c,4 d and the productions stopes 13 a,13 b,13 c have a rectangular cross-section. However, in another form of the invention, the de-stressing slots 3 a,3 b,3 c,3 d and start-slots 4 a,4 b,4 c,4 d may also have elliptical or at least elongated cross-section. In one form of the invention, at least one of the production stopes 13 a,13 b,13 c,13 d may have elliptical, circular, or other irregular cross-sections. Furthermore, the inclination of start-slots, slots and stopes could be varied for adaptation purposes as indicated in FIGS. 4 c-g and 4 k.

FIG. 6 a, 6 b illustrate the de-stressing phase at an early stage of the Raise Caving mining method according to the invention, and FIG. 8 a, 8 b illustrate a more advanced stage of the de-stressing phase. FIG. 10 a, 10 b mainly illustrate the production phase and extraction of ore from the ore body. The figures are simplified to facilitate the understanding of the method; therefore, the figures only show a small part of a rock mass and Raise Caving mining method.

FIG. 10 a, 10 b illustrate stepwise development of the de-stressing infrastructure, such as slot raises 1 a,1 b,1 c,1 d, slot access level 2, raise levels 5.1,5.2 and slot drawpoints 21, and the production infrastructure, such as draw level 8, stope drawpoints 22, intermediate draw levels 5.1,5.1.1,5.2,5.2.1, rock passes 11 a,11 b and production raises 6 a,6 b,6 c. Furthermore, FIG. 10 a,10 b illustrate the development of slots 3 a,3 b,3 c,3 d and start-slots 4 a,4 b,4 c,4 d and the mining of the stopes 13 a,13 b,13 c according to the invention. It is essential that the slot development has progressed sufficiently such that a favourable stress environment in the rock mass is created to ensure safe development and expansion of production infrastructure and mining of stopes.

Specifically, the Raise Caving mining method further comprises implementing a mining sequence for providing the favourable stress environment and for controlling mining induced seismicity in the active mining area. The term “mining sequence” refers to the sequence of mining activities, which should be followed in order to achieve the overall goals of extraction of the ore body as complete as possible, the safety and economy of the mining operation, considering factors, rock mechanical constraints and other factors. Preferably, the mining sequence is adapted to and determined by production and/or ore body geometry and/or rock mechanics consideration thereby controlling mining induced seismicity and high stresses.

Preferably the mining sequence comprises development of the slot 3 a,3 b,3 c,3 d ahead of development of the production stopes 13 a,13 b,13 c respectively where the roof of the slot 3R is a predetermined vertical distance ahead of the roof of the production stope 13R, in order to ensure that the production stopes 13 a,13 b,13 c are mined in de-stressed rock mass. It should be noted that the slots do not have to be developed to the full length prior to developing the production stope adjacent the respective slot.

Several production stapes 13 a,13 b,13 c may be in production at the same time, however a vertical distance between the roofs of neighboring production stopes 13 a,13 b,13 c is recommended in order to avoid negative interrelations. Production stope footprints of more than 1000 m² appear to be feasible at present.

FIGS. 3, 4 l, and 6-10, 11 show schematically different examples of mining sequences of the de-stressing phase and the production phase according to the Raise Caving mining method for providing the favourable stress environment. By implementing a mining sequence, mining induced seismicity and high stresses can be controlled in the active mining area.

The Raise Caving mining method, as shown in the figures illustrates only a limited active mining area. However, the mining method may extend further both vertically and horizontally, not shown in the figures. Preferably, the steps of the method are repeated to a larger area until the desired part of the ore body has been extracted.

The Raise Caving mining method according to the present invention is a flexible method allowing for changes in mine layout and mining sequence on short notice and according to needs, production, ore body geometry, prevailing rock mass conditions, prevailing stress situation etc.

The mine layout such as position of slots, stopes and raises, inclination of raises, level spacing, shape of slots, start-slots and stopes, etc. and other infrastructure can be adapted to local ore body shapes, stress situation, rock mass properties etc. Preferably, the mine layout is adapted to and determined by production, ore body geometry, rock mass conditions, stress situation etc.

Preferably, the mine layout and the mining sequence can be adjusted on short notice to account for unforeseen circumstances and can be adapted flexibly. E.g. site-specific drill and blast patterns, adaptable stope and slot cross-section, adaptable slot orientations, adaptable draw strategies etc. may be implemented. Furthermore, cross-sections of stopes can be adjusted to ore body boundaries with orientation and length of individual drill holes.

Moreover, changes in the mine layout and the mining sequence can be made on a short to medium term notice, because Raise Caving mining method requires a minimum amount of infrastructure development in advance. This circumstance is a powerful possibility to adopt mine design to gained experiences dynamically. However, rock mechanical considerations must be considered in such a flexible mine design. For example, production raises must be placed in de-stressed rock mass or rock mass having favourable stress environment. Overall, the flexibility in the Raise Caving mining method is much improved in comparison to prior art caving methods. Prior art caving methods are very rigid and do not allow changes at all or have very limited or expensive possibilities for adaptions after infrastructure development started or caving was initiated, respectively.

Certain elements of Raise Caving mining method could be applied in other ways as well. Preferably, at least one de-stressing slot is implemented in another mining method such as block and panel caving method, for generating a stress-shadow and creating a favourable stress environment to provide protection of critical infrastructure in such mining method.

In another form of the invention at least one production stope is connected to a previously caved area thereby allowing previously caved masses to fill up the at least one production stope. For example, the stope roof may be connected by the stoping process to an area located above the stope, wherein said area has caved earlier.

Furthermore, in another form of the invention parts of a stope are backfilled. This backfill provides support to the surrounding rock mass. Moreover, the stope can be used as a waste storage instead of transporting waste to other locations.

Furthermore, in one form of the invention the method comprises a step of monitoring the production stapes 13 a,13 b,13 c via the production raises 6 a,6 b,6 c. Efficient and reliable control of the stoping process is thereby achieved. Preferably, cave stall and the associated risk of an air blast are also controlled via the production raises 6 a,6 b,6 c using said monitoring methods.

FIG. 12 schematically illustrates a Raise Caving mining infrastructure 902 according to one example. The mining infrastructure 902 comprises an automatic or semi-automatic control system 901 electrically coupled to a control circuitry 900.

The Raise caving mining infrastructure 902 is configured for mining ore from an ore body 61. The mining infrastructure 902 comprises at least two slots 3 a, 3 b in a rock mass RM and further comprises a pillar 9 a of the rock mass RM to separate adjacent slots 3 a, 3 b in order to create a favourable stress environment in the rock mass to provide protection for the mining infrastructure 902. The mining infrastructure 902 further comprises at least one production raise 6 a within the rock mass RM providing the favourable stress environment and at least one production stope 13 a progressed upwards by mining from the at least one production raise 6 a. The mining infrastructure 902 further comprises a transport device 904 configured to draw ore from the production stope 13 a.

Alternatively, the respective slot 3 a, 3 b being associated with a stress-shadow S at certain locations adjacent to the slot 3 a, 3 b, wherein said stress-shadow S de-stresses the rock mass RM thereby creating said favourable stress environment. Alternatively, at least one slot raise may be developed 1 a,1 b from a drift arranged on a slot access level 2 upwards to a drift arranged on a level 5.1 arranged above the slot access level 2 in the rock mass. Alternatively, at least one of said slots 3 a,3 b may developed from said at least one slot raise 1 a,1 b by blasting upwards from the drift arranged on the slot access level 2 to the drift arranged on the level 5.1 arranged above the slot access level 2 in the rock mass. Alternatively, at least one start-slot 4 a,4 b,4 c may be developed from a slot access level 2 to a predetermined vertical extent, wherein the start-slot generates a stress-shadow S to provide protection for production infrastructure located above the slot access level 2. Alternatively, a continuous start-slot 20 may be developed by joining at least two start-slots 4 a,4 b. Alternatively, at least one of the slots 3 a,3 b may be developed from the roof 4R of one of the start-slots 4 a,4 b, wherein the area of the slot roof 3R is smaller than the area of the start-slot roof 4R. Alternatively, a draw level 8 may be developed in rock mass located in a favourable stress environment. Alternatively, the draw level 8 may comprise draw infrastructure such as slot drawpoints 21, stope drawpoints 22 and drifts, wherein the drawpoints 21,22 are configured to be long-term and stationary. Alternatively, the hangingwall 62 may be caved in order to fill up at least a part of at least one mined out production stope. Alternatively, the pillar may be extracted. Alternatively, the pillars 9 a,9 b,9 c may be extracted to facilitate hangingwall caving. Alternatively, intermediate draw levels may be developed in order to improve extraction of ore from the stope.

The Raise Caving mining infrastructure 902 may further comprise a machinery 910 that may comprise a drilling and/or charging device (not shown) configured for developing the slots 3 a, 3 b and/or the pillar 9 a and/or the production stope 13 a and/or the production raise 6 a. The machinery 910 may be coupled to a transport device 904 configured for drawing ore from the production stope 13 a. The transport device 904 may comprise loaders and/or trucks and/or continuous draw machinery with conveyors. configured for drawing, loading and transporting ore from the production stope.

The machinery 910 may be configured for drilling and/or charging the rock mass RM from inside the raise by means of a drilling and/or charging device (not shown). The drilling and/or charging device may comprise a drilling bore and/or blast charging equipment configured to develop the at least one production stope 13 a progressed upwards by mining from the at least one production raise 6 a. The machinery 910 may be installed on a platform (not shown), which is configured to be moved by a shaft hoist system (not shown) within the raise. The machinery 910 may be configured for hydrofracturing from inside the raise. The machinery 910 may be configured for pre-conditioning and/or pre-breaking from inside the raise. The machinery 910 may be configured for installing support and/or reinforcement for the rock mass from inside the raise. The machinery 910 may be configured to be operated by remote control. The machinery 910 may be configured for semiautomation or full automation. The machinery 910 may be configured to be operated manually. The machinery 910 may be configured to be operated by an automatic or semi-automatic control system 901 in remote control mode and/or in automatic control mode and/or in semi-automatic control mode and/or in manual mode.

The Raise Caving mining infrastructure 902 illustrated in FIG. 12 may further comprise a monitoring system 920 configured for monitoring a Raise Caving mining infrastructure 902 configured for mining ore from an ore body 61.

The monitoring system 920 comprises monitorings means 921 configured for monitoring development of at least two slots 3 a,3 b in a rock mass and leaving a pillar 9 a of rock mass to separate adjacent slots 3 a,3 b. The monitoring system 920 comprises monitoring means 922 for monitoring creation of a favourable stress environment in the rock mass to provide protection for mining infrastructure. The monitoring system 920 comprises monitoring means 923 for monitoring development of at least one production raise 6 a, 6 b within the rock mass providing the favourable stress environment. The monitoring system 920 comprise monitoring means for monitoring mining progressing upwards at least one production stope 13 a from the at least one production raise 6 a. The monitoring system 920 comprises monitoring means 924 for monitoring at least one pillar 9 a. The monitoring system 920 may comprise monitoring means 925 for monitoring draw of ore from the production stope 13 a.

The monitoring system 920 may be configured for monitoring seismicity and/or stress and/or deformations in the rock mass where the Raise Caving mining infrastructure (902) is located. The monitoring system 920 may be configured for monitoring seismicity and/or stress and/or deformations in the active mining area. The monitoring system 920 may be configured for monitoring interaction of the production stope and the pillars located adjacent the production stope. The monitoring system 920 may be configured for monitoring the shape of the excavations such as the .raise, the stope and the slots. The monitoring system 920 may be configured for monitoring the conditions of the excavation such as stability and/or instability of said excavation. The monitoring system 920 may be configured for monitoring the conditions of the pillar such as fracture zones. The monitoring system 920 may be configured for monitoring the ore flow and/or broken rock mass inside the stope. The monitoring system 920 may be configured for monitoring the production stope 13 a via the production raise. The monitoring system 920 may be configured for monitoring the slot regarding for example stability, shape, ore flow or broken rock mass.

The monitoring system 920 may be configured to communicate with and be operated by the automatic or semi-automatic control system 901 in remote control mode and/or in automatic control mode and/or in semi-automatic control mode and/or manually controlled mode.

The monitoring system 920 comprises amongst others a plurality of monitoring means, a central monitoring unit, data collection units, data storage means, communication devices and/or data analysis tools. The monitoring system 920 may be configured to communicate with the automatic or semi-automatic control system 901 and to transmit data and information generated by the monitoring system to the automatic or semi-automatic control system 901. The monitoring means comprises for example seismic monitoring system, time domain reflectometry technology, inspections through open bore holes, cavity scanners, sensors, marker or geophones.

The Raise Caving mining infrastructure 902 illustrated in FIG. 12 may further comprise an automatic or semi-automatic control system 901 which is electrically coupled to a control circuitry 900 configured to control the Raise Caving mining infrastructure 902 configured for mining ore from an ore body 61 and/or an exemplary Raise Caving mining method herein disclosed.

Furthermore the automatic or semi-automatic control system 901 may be configured for draw control. The automatic or semi-automatic control system 901 may be configured for implementing the mining sequence. The automatic or semi-automatic control system 901 may be configured for implementing the mining layout. The automatic or semi-automatic control system 901 may be configured for implementing a draw strategy. The automatic or semi-automatic control system 901 wherein the automatic or semi-automatic control system 901 may be configured for controlling that the Raise caving mining method steps are repeated to a larger area in the rock mass.

FIG. 13 illustrates a flowchart showing an exemplary raise caving mining method. The method comprises a first step 701 starting the method. A second step 702 comprises the performance of the exemplary method. A third step 703 comprises stoping the method. The second step 702 may comprise the following steps; developing at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise within the rock mass providing the favourable stress environment, progressing upwards by mining at least one production stope from the at least one production raise, and drawing ore from the production stope.

FIG. 14 illustrates a flowchart showing a further example of a raise caving mining method. The indicated method steps in the example may be performed in any order. The method comprises a first step 801 starting the method. A second step 802 may comprise developing at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise within the rock mass providing the favourable stress environment, progressing upwards by mining at least one production stope from the at least one production raise, and drawing ore from the production stope. A third step 803 comprises de-stressing the rock mass thereby creating favourable stress environment by developing each slot generating a stress-shadow at certain locations adjacent to the slot, wherein said stress-shadow de-stresses the rock mass thereby creating said favourable stress environment. A fourth step 804 may comprise developing at least one slot from a drift arranged on a first sublevel by means of drilling and charging rounds upwards to a drift arranged on a second sublevel arranged above the first sublevel in the rock mass, blasting and loading said rounds in a retreat manner.

A fifth step 805 may comprise developing at least one slot raise from a drift arranged on a slot access level upwards to a drift arranged on a level arranged above the slot access level in the rock mass.

A sixth step 806 comprises developing at least one of said slots from said at least one slot raise by drilling and blasting upwards from the drift arranged on the slot access level to the drift arranged on the level arranged above the slot access level in the rock mass.

A seventh step 807 comprises developing said production raise in the favourable stress environment at certain locations created adjacent said slots. An eight step 808 comprises controlling by means of the pillar the stress magnitude in the rock mass at the position in the rock mass where the following slot will subsequently be developed, thereby creating a favourable stress environment to enable development of the following slot.

A ninth step 809 comprises implementing a mining sequence for providing the favourable stress environment in the active mining area. A tenth step 810 comprises controlling of mining induced seismicity in the active mining area by implementing said mining sequence. An eleventh step 811 may comprise developing at least one start-slot from the slot access level to a predetermined vertical extent in order to generate a stress-shadow to provide protection for production infrastructure located above the slot access level. A twelfth step 812 comprises repeating the steps of the raise caving mining method to a larger area in the rock mass, to exploit the ore body. A thirteens step 813 comprises stoping the method.

FIG. 15 illustrates a control circuitry 900 (such as a central control processor or other computer device) adapted to operate an automatic or semi-automatic control system 901 of a mining infrastructure 902, which automatic or semi-automatic control system is configured to perform any exemplary Raise Caving mining method herein disclosed.

The control circuitry 900 is configured to control any exemplary raise caving mining method or methods disclosed herein. The control circuitry 900 comprises a data medium, configured for storing a data program P. The data program P is configured (programmed) for controlling the automatic or semi-automatic control system 901 and/or for controlling the machinery shown in FIG. 12 . The data medium comprises a program code readable by the control circuitry 900 for performing any of the exemplary methods herein described, when the data medium is run on the control circuitry 900.

The control circuitry 900 is electrically coupled to a machinery (not shown) comprising a drilling and/or blasting device (not shown). The control circuitry 900 is further configured to communicate with the monitoring system 920 via wired and/or wireless communication system to transmit and/or receive monitoring data. The control circuitry 900 is configured to provide that the automatic or semi-automatic control system 901 and/or machinery each performs the method of; developing at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise within the rock mass providing the favourable stress environment, progressing upwards by mining at least one production stope from the at least one production raise, and drawing ore from the production stope.

The control circuitry 900 may thus also be configured for maneuvering a transport device, such as a remote controlled mining truck (not shown) for said drawing of ore from the production stope.

The control circuitry 900 comprises a computer and a non-volatile memory NVM 1320, which is a computer memory that can retain stored information even when the computer is not powered.

The control circuitry 900 further comprises a processing unit 1310 and a read/write memory 1350. The NVM 1320 comprises a first memory unit 1330. A computer program (which can be of any type suitable for any operational data) is stored in the first memory unit 1330 for controlling the functionality of the control circuitry 900. Furthermore, the control circuitry 900 comprises a bus controller (not shown), a serial communication unit (not shown) providing a physical interface, through which information transfers separately in two directions.

The control circuitry 900 may comprise any suitable type of I/O module (not shown) providing input/output signal transfer, an A/D converter (not shown) for converting continuously varying signals from a sensor arrangement (not shown) of the control circuitry 900 configured to determine actual status of the machinery and/or the automatic or semi-automatic control system 901. The control circuitry 900 is configured to, from received control signals, determine the positions of the machinery, regarding drilling and operation of the explosive material charging, into binary code suitable for the computer, and from other operational data.

The control circuitry 900 also comprises an input/output unit (not shown) for adaptation to time and date. The control circuitry 900 comprises an event counter (not shown) for counting the number of event multiples that occur from independent events in operation of the machinery and/or the automatic or semi-automatic control system 901.

Furthermore, the control circuitry 900 includes interrupt units (not shown) associated with the computer for providing a multi-tasking performance and real time computing. The NVM 1320 also includes a second memory unit 1340 for external sensor check of the sensor arrangement.

A data medium for storing a program P may comprise program routines for automatically adapting the operation of the machinery and/or the automatic or semi-automatic control system 901 in accordance with operational data regarding e.g. the actual status showing the development of the Raise Caving mining infrastructure and the Raise Caving mining method.

The data medium for storing the program P comprises a program code stored on a medium, which is readable on the computer, for causing the control circuitry 900 to perform the method and/or method steps described herein.

The program P further may be stored in a separate memory 1360 and/or in the read/write memory 1350. The program P, in this embodiment, is stored in executable or compressed data format.

It is to be understood that when the processing unit 1310 is described to execute a specific function that involves that the processing unit 1310 may execute a certain part of the program stored in the separate memory 1360 or a certain part of the program stored in the read/write memory 1350.

The processing unit 1310 is associated with a data port 1399 adapted for electrical data signal communication via a first data bus 1315 provided to be coupled to the machinery and/or the automatic or semi-automatic control system 901 for performing any of the exemplary method steps herein described.

The non-volatile memory NVM 1320 is adapted for communication with the processing unit 1310 via a second data bus 1312. The separate memory 1360 is adapted for communication with the processing unit 610 via a third data bus 1311. The read/write memory 1350 is adapted to communicate with the processing unit 1310 via a fourth data bus 1314. After that the received data is temporary stored, the processing unit 1310 will be ready to execute the program code, according to the above-mentioned method.

Preferably, signals (received by the data port 1399) comprise information about operational status of the machinery and/or the automatic or semi-automatic control system 901.

Information and data may be manually fed, by an operator, to the control circuitry 900 via a suitable communication device, such as a computer display or a touchscreen. The exemplary methods herein described may also be partially executed by the control circuitry 900 by means of the processing unit 1310, which processing unit 1310 runs the program P being stored in the separate memory 1360 or the read/write memory 1350. When the control circuitry 900 runs the program P, anyone of the exemplary methods disclosed herein will be executed.

The foregoing description of the preferred embodiments is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the embodiments to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described to best explain the principles and practical applications, and hence make it possible for specialists to understand the invention for various embodiments and with various modifications that are applicable to its intended use.

The present invention is of course not in any way restricted to the examples described above, but many possibilities to modifications, or combinations of the described embodiments thereof should be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention as defined in the appended claims. 

1-94. (canceled)
 95. A raise caving mining method for mining ore from an ore body comprising: developing at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise within the rock mass providing the favorable stress environment, and progressing upwards by mining at least one production stope from the at least one production raise, and drawing ore from the production stope.
 96. The method according to claim 95 further comprising; generating a stress-shadow (S) by each slot at certain locations adjacent to the slot, wherein said stress-shadow (S) de-stresses the rock mass thereby creating said favourable stress environment.
 97. The method according to claim 95, wherein said production raise is developed in the favourable stress environment at certain locations created adjacent said slots.
 98. The method according to claim 95, wherein said pillar of rock mass provides control of stress magnitude in the rock mass at the position in the rock mass where the following slot will subsequently be developed thereby creating a favourable stress environment to enable development of the following slot.
 99. The method according to claim 95, further comprising implementing a mining sequence for providing the favourable stress environment in the active mining area and for controlling of mining induced seismicity in the active mining area.
 100. The method according to claim 95, further comprising developing at least one slot from a drift arranged on a first sublevel by means of upwards drilling and blasting rounds in a retreat manner to a drift arranged on a second sublevel arranged above the first sublevel in the rock mass.
 101. The method according to claim 95, further comprising developing at least one slot raise from a drift arranged on a slot access level upwards to a drift arranged on a level arranged above the slot access level in the rock mass.
 102. The method according to claim 101, further comprising developing at least one of said slots from said at least one slot raise by blasting upwards from the drift arranged on the slot access level to the drift arranged on the level arranged above the slot access level in the rock mass.
 103. The method according to claim 101, further comprising developing at least one start-slot from the slot access level to a predetermined vertical extent in order to generate a stress-shadow S to provide protection for production infrastructure located above the slot access level.
 104. The method according to claim 103, wherein said start-slot is developed from at least one slot raise by blasting upwards along the slot raise from the drift arranged at the slot access level to the predetermined vertical extent.
 105. The method according to claim 103, further comprising developing a continuous start-slot from at least two start-slots in order to generate a stress-shadow S to provide protection for production infrastructure located above the slot access level and adjacent to the start-slot.
 106. The method according to claim 103, further comprising developing at least one of the slots from the roof of one of the start-slots, wherein the area of the slot roof is smaller than the area of the start-slot roof.
 107. The method according to claim 95, wherein at least one of said slots is vertical or inclined.
 108. The method according to claim 95, wherein at least one of said slots is arranged in a contact area between the ore body and the surrounding rock mass formations.
 109. The method according to claim 95, further comprising developing a draw level in rock mass located in a favourable stress environment.
 110. The method according to claim 95, further comprising generating a favorable stress environment by the production stope to protect mining infrastructure in the vicinity of the production stope.
 111. The method according to claim 95, further comprising mining the production stope by drilling and blasting.
 112. The method according to claim 95, further comprising mining the production stope by caving.
 113. The method according to claim 95, further comprising extracting a pillar.
 114. The method according to claim 113, further comprising extracting said pillar by degrading the pillar strength by decreasing the pillar width-to-height ratio due to nearby stope mining and facilitating pillar yielding and self-destruction.
 115. The method according to claim 95, further comprising extracting a pillar by means of caving.
 116. The method according to claim 95, further comprising extracting a pillar by means of drilling and blasting.
 117. The method according to claim 95, further comprising caving parts of a hangingwall, in order to fill up at least a part of at least one mined out production stope.
 118. The method according to claim 95, further comprising caving a hanging wall facilitated by extraction of pillars thereby removing the hangingwall support provided by the pillars.
 119. The method according to claim 95, further comprising developing a slot from a raise, where the raise is not located inside the slot.
 120. The method according to claim 95, further comprising preventing premature caving of hangingwall by the presence of broken rock mass functioning as a temporary hangingwall support inside the slots and/or stope.
 121. The method according to claim 95, further comprising a de-stressing phase for generating and expanding the favourable stress environment in the rock mass, to protect mining infrastructure, in particular the infrastructure in the production area, and a production phase for extraction of ore from the ore body, and wherein de-stressing phase and the production phase are integrated such that in a certain mining area the production phase benefits from the de-stressing phase.
 122. The method according to claim 95, wherein the mining sequence comprises development of the slot ahead of development of the respective production stope where the roof of the slot is a predetermined vertical distance ahead of the roof of the production stope, such that the production stope is mined in favourable stress environment.
 123. The method according to claim 95, further comprising monitoring the production stope via the production raise.
 124. The method according to claim 95, further comprising controlling risk of air blast and cave stall in the production stope via the production raise.
 125. The method according to claim 95, further comprising backfilling parts of the production stope.
 126. A Raise Caving mining infrastructure configured for mining ore from an ore body, which mining infrastructure comprises: at least two slots in a rock mass (RM); a pillar of rock mass (RM) to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for the mining infrastructure; at least one production raise within the rock mass (RM) providing the favourable stress environment; at least one production stope progressed upwards by mining from the at least one production raise; and a transport device configured to draw ore from the production stope.
 127. The Raise Caving mining infrastructure according to claim 126, wherein the slot is associated with a stress-shadow (S) at certain locations adjacent to the slot, wherein said stress-shadow (S) de-stresses the rock mass thereby creating said favourable stress environment.
 128. A monitoring system configured for monitoring a Raise Caving mining infrastructure configured for mining ore from an ore body according to claim 126, which monitoring system comprises: monitoring means for monitoring development of at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slots and monitoring means for monitoring creation of a favourable stress environment in the rock mass to provide protection for mining infrastructure; and/or monitoring means for monitoring development of at least one production raise within the rock mass providing the favourable stress environment; and/or monitoring means for monitoring mining progressing upwards at least one production stope from the at least one production raise; and/or monitoring means for monitoring at least one pillar; and wherein the monitoring system is configured for monitoring seismicity and/or stress and/or deformations in the rock mass where the Raise Caving mining infrastructure is located; and wherein the monitoring system is configured to communicate with and be operated by an automatic or semi-automatic control system; and wherein the monitoring system is configured to transmit data and information generated by the monitoring system to the automatic or semi-automatic control system.
 129. The monitoring system according to claim 128 wherein the monitoring system is configured for monitoring seismicity and/or stress and/or deformations in the active mining area.
 130. A machinery comprising a drilling and/or charging device configured for: developing at least two slots in a rock mass (RM); and/or developing a pillar of rock mass to separate adjacent slots in order to create a favourable stress environment in the rock mass to provide protection for a mining infrastructure; and/or developing at least one production raise within the rock mass providing the favourable stress environment; and/or developing at least one production stope progressed upwards by mining from the at least one production raise; and/or drawing ore from the production stope by means of a transport device configured to draw ore from the production stope.
 131. The machinery according to claim 130, wherein the machinery is configured for drilling and/or charging the rock mass (RM) from inside the raise.
 132. The machinery according to claim 130, wherein the drilling and/or charging device comprises a drilling bore and/or charging equipment configured to develop the at least one production stope progressed upwards by mining from the at least one production raise.
 133. The machinery according to claim 130, wherein the machinery is installed on a platform, which is configured to be moved by a shaft hoist system within the raise.
 134. An automatic or semi-automatic control system of a mining infrastructure according to claim 126, wherein the automatic or semi-automatic control system is electrically coupled to a control circuitry configured to control the method according to claim 95; and wherein the control circuitry comprises a data medium, configured for storing a data program P which is programmed for controlling the automatic or semi-automatic control system and/or for controlling the machinery and/or for controlling the monitoring system; and wherein the control circuitry; and wherein the control circuit is configured to communicate with the monitoring system via wired and/or wireless communication system to transmit and/or receive monitoring data.
 135. The automatic or semi-automatic control system according to claim 132, wherein the automatic or semi-automatic control system is configured for draw control.
 136. The automatic or semi-automatic control system according to claim 132, wherein the automatic or semi-automatic control system is configured for implementing the mining sequence.
 137. A data medium, configured for storing a data program (P), configured for controlling the automatic or semi-automatic control system according to claim 134 and/or configured for controlling the machinery according to claim 130, and/or controlling the monitoring system, said data medium comprises a program code readable by the control circuitry for performing the method according to claim 95 when the data medium is run on the control circuitry. 